Hi ,I am facing this same issue, as mentioned in this Forum: http://social.technet.microsoft.com/Forums/en-US/exchangesvrdeploy/thread/5cb79acf-6fed-4e99-b092-6e3f923e325b/All the users outlook are disconnected, but Info Store and Sys attendat are working, I just need to manually restart the Info Store Serive and everything is back to normal.can you suggest if the disable checksum will help as mentioned in the forum.Also request to provide the steps to do it, and possible reason for the issue.Scenario: AD 2003 Sp2 with all patches, Exchange 2007 SP1 single server with all roles in 1 server.Event Type: Error Event Source: MSExchange System Attendant Mailbox Event Category: General Event ID: 4001 Date: 9/27/2009 Time: 10:02:46 AM User: N/A Computer: INEXC10 Description: A transient failure has occurred. The problem may resolve itself in awhile. The service will retry in 56 seconds. Diagnostic information: Cannot open mailbox /o=MYDOMAININ/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=INEXC10/cn=Microsoft System Attendant. Microsoft.Exchange.Data.Storage.ConnectionFailedTransientException: Cannot open mailbox /o=MYDOMAININ/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=INEXC10/cn=Microsoft System Attendant. ---> Microsoft.Mapi.MapiExceptionNetworkError: MapiExceptionNetworkError: Unable to make connection to the server. (hr=0x80040115, ec=-2147221227) Diagnostic context: ...... Lid: 10648 dwParam: 0x6D9 Msg: EEInfo: Generating component: 2 Lid: 14744 dwParam: 0x6D9 Msg: EEInfo: Status: 1753 Lid: 9624 dwParam: 0x6D9 Msg: EEInfo: Detection location: 501 Lid: 13720 dwParam: 0x6D9 Msg: EEInfo: Flags: 0 Lid: 11672 dwParam: 0x6D9 Msg: EEInfo: NumberOfParameters: 4 Lid: 8856 dwParam: 0x6D9 Msg: EEInfo: prm[0]: Unicode string: ncacn_ip_tcp Lid: 8856 dwParam: 0x6D9 Msg: EEInfo: prm[1]: Unicode string: INEXC10.in.MYDOMAIN.local Lid: 12952 dwParam: 0x6D9 Msg: EEInfo: prm[2]: Long val: -1527653632 Lid: 15000 dwParam: 0x6D9 Msg: EEInfo: prm[3]: Pointer val: 0x0000000002C17200 Lid: 19778 Lid: 27970 StoreEc: 0x80040115 Lid: 17730 Lid: 25922 StoreEc: 0x80040115 at Microsoft.Mapi.MapiExceptionHelper.ThrowIfError(String message, Int32 hresult, Int32 ec, DiagnosticContext diagCtx) at Microsoft.Mapi.ExRpcConnection.Create(ConnectionCache connectionCache, ExRpcConnectionCreateFlag createFlags, ConnectFlag connectFlags, String serverDn, String userDn, String user, String domain, String password, String httpProxyServerName, Int32 ulConMod, Int32 lcidString, Int32 lcidSort, Int32 cpid, Int32 cReconnectIntervalInMins, Int32 cbRpcBufferSize, Int32 cbAuxBufferSize) at Microsoft.Mapi.ConnectionCache.OpenMapiStore(String mailboxDn, Guid mailboxGuid, Guid mdbGuid, ClientIdentityInfo clientIdentity, String userDnAs, OpenStoreFlag openStoreFlags, CultureInfo cultureInfo, String applicationId) at Microsoft.Mapi.ConnectionCache.OpenMailbox(String mailboxDn, Guid mailboxGuid, Guid mdbGuid, WindowsIdentity windowsIdentityAs, String userDnAs, OpenStoreFlag openStoreFlags, CultureInfo cultureInfo, String applicationId) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) --- End of inner exception stack trace --- at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Data.Storage.MailboxSession.Initialize(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags) at Microsoft.Exchange.Data.Storage.MailboxSession.CreateMailboxSession(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Data.Storage.MailboxSession.OpenAsAdmin(ExchangePrincipal mailboxOwner, CultureInfo cultureInfo, String clientInfoString, Boolean useLocalRpc, Boolean ignoreHomeMdb) at Microsoft.Exchange.Data.Storage.MailboxSession.OpenAsAdmin(ExchangePrincipal mailboxOwner, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Servicelets.SystemAttendantMailbox.Servicelet.Work() For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp . Thank you in advanceRegards, Kiran B.

Hi, I am facing a peculiar issue, suddenly the Outlook gets disconnected, and on checking the INFO Store its stopped I, just need to manually Start it, and everything starts working.AD 2003, Exchange 2007 SP1 all roles on 1 server. Also I found in one of the forums, disabling the checksum helps. http://social.technet.microsoft.com/Forums/en-US/exchangesvrdeploy/thread/5cb79acf-6fed-4e99-b092-6e3f923e325b/ Can you suggest which is the value, also why this issues occurs. Thank you all in advance. Event Type: Error Event Source: MSExchange System Attendant Mailbox Event Category: General Event ID: 4001 Date: 9/27/2009 Time: 10:02:46 AM User: N/A Computer: INEXC10 Description: A transient failure has occurred. The problem may resolve itself in awhile. The service will retry in 56 seconds. Diagnostic information: Cannot open mailbox /o=mydomainIN/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=INEXC10/cn=Microsoft System Attendant. Microsoft.Exchange.Data.Storage.ConnectionFailedTransientException: Cannot open mailbox /o=mydomainIN/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=INEXC10/cn=Microsoft System Attendant. ---> Microsoft.Mapi.MapiExceptionNetworkError: MapiExceptionNetworkError: Unable to make connection to the server. (hr=0x80040115, ec=-2147221227) Diagnostic context: ...... Lid: 10648 dwParam: 0x6D9 Msg: EEInfo: Generating component: 2 Lid: 14744 dwParam: 0x6D9 Msg: EEInfo: Status: 1753 Lid: 9624 dwParam: 0x6D9 Msg: EEInfo: Detection location: 501 Lid: 13720 dwParam: 0x6D9 Msg: EEInfo: Flags: 0 Lid: 11672 dwParam: 0x6D9 Msg: EEInfo: NumberOfParameters: 4 Lid: 8856 dwParam: 0x6D9 Msg: EEInfo: prm[0]: Unicode string: ncacn_ip_tcp Lid: 8856 dwParam: 0x6D9 Msg: EEInfo: prm[1]: Unicode string: INEXC10.in.mydomain.local Lid: 12952 dwParam: 0x6D9 Msg: EEInfo: prm[2]: Long val: -1527653632 Lid: 15000 dwParam: 0x6D9 Msg: EEInfo: prm[3]: Pointer val: 0x0000000002C17200 Lid: 19778 Lid: 27970 StoreEc: 0x80040115 Lid: 17730 Lid: 25922 StoreEc: 0x80040115 at Microsoft.Mapi.MapiExceptionHelper.ThrowIfError(String message, Int32 hresult, Int32 ec, DiagnosticContext diagCtx) at Microsoft.Mapi.ExRpcConnection.Create(ConnectionCache connectionCache, ExRpcConnectionCreateFlag createFlags, ConnectFlag connectFlags, String serverDn, String userDn, String user, String domain, String password, String httpProxyServerName, Int32 ulConMod, Int32 lcidString, Int32 lcidSort, Int32 cpid, Int32 cReconnectIntervalInMins, Int32 cbRpcBufferSize, Int32 cbAuxBufferSize) at Microsoft.Mapi.ConnectionCache.OpenMapiStore(String mailboxDn, Guid mailboxGuid, Guid mdbGuid, ClientIdentityInfo clientIdentity, String userDnAs, OpenStoreFlag openStoreFlags, CultureInfo cultureInfo, String applicationId) at Microsoft.Mapi.ConnectionCache.OpenMailbox(String mailboxDn, Guid mailboxGuid, Guid mdbGuid, WindowsIdentity windowsIdentityAs, String userDnAs, OpenStoreFlag openStoreFlags, CultureInfo cultureInfo, String applicationId) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) --- End of inner exception stack trace --- at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString, Boolean secondTry) at Microsoft.Exchange.Data.Storage.ConnectionCachePool.OpenMailbox(String serverDn, String userDn, String mailboxDn, Guid mailboxGuid, Guid mdbGuid, Object identity, ConnectFlag connectFlag, OpenStoreFlag openStoreFlag, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Data.Storage.MailboxSession.Initialize(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags) at Microsoft.Exchange.Data.Storage.MailboxSession.CreateMailboxSession(LogonType logonType, ExchangePrincipal owner, DelegateLogonUser delegateUser, Object identity, OpenMailboxSessionFlags flags, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Data.Storage.MailboxSession.OpenAsAdmin(ExchangePrincipal mailboxOwner, CultureInfo cultureInfo, String clientInfoString, Boolean useLocalRpc, Boolean ignoreHomeMdb) at Microsoft.Exchange.Data.Storage.MailboxSession.OpenAsAdmin(ExchangePrincipal mailboxOwner, CultureInfo cultureInfo, String clientInfoString) at Microsoft.Exchange.Servicelets.SystemAttendantMailbox.Servicelet.Work() For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp .Regards, Kiran B.

HI, below article nicely describe about offload Checksumming,I have quote below statements from there. Quote When data comes in through a network, it's "checksummed," meaning the data is checked against a checksum (or validation code) in the headers in the packets it was delivered in. If the data and checksum don't match, the packet is determined to be bad and has to be retransmitted. To speed things up, some network cards can "offload" the checksumming, i.e., perform the checksumming on the network card itself, rather than leave the job to the CPU. This frees up the CPU to do that much more work on its own and on a server with extremely high network throughput, that much CPU savings can add up. To disable checksum offloading: 1. Open the Registry and navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters. 2. Add a new DWORD value named DisableTaskOffload and set it to 1. 3. You may need to restart the system to make these changes take effect. Note:-Please take the backup of registry before dochanges. Resource Disable checksum offloading to resolve network slowdown caused by Windows Firewall Regards Chinthaka Shameera | MCITP: EA | MCSE: M | http://howtoexchange.wordpress.com/

http://www.microsoft.com/technet/support/ee/transform.aspx?ProdName=Exchange&ProdVer=8.0&EvtID=4001&EvtSrc=MSExchange+System+Attendant+Mailbox&LCID=1033 Also run EXBPA to make sure all settings are up to the markVinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Duplicate ForumVinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|