The exchange server asks for username and password even though this has not been changed. Restarting the Information store solves the problem but it reoccurs in a day or two. We are Using SBE 2003 server. If we restart the server the information store service will not restart and we have to start the services manually everytime eventhough its set for automatic start. Also recives the error: "Accept clients on external interface MAPIRPC failed with error 0x4b1Server: SBS2003Antivirus: Symantec End Point protectionThanks for any help on this issue.Michael

Michael,Are teh users connected on MAPI or RPC over Https? If Mapi , can they loging to domain fine? If yes and the problem is only with the mail box login, then check the performance of the server. Try to put /3GB switch on the boot.iniIf they are on RPC over https, things can be different. Might be DNS or RPC over Https configuration etc that you need to check.Raj

Hi, 1. Open the Registry Editor by clicking Start > Run. Type regedit in the box, and then press Enter. 2. Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\ 3. In the right pane, double-click lmcompatibilitylevel. 4. In the Value data box, type a value of 0 and then click OK. 5. Close Registry Editor and restart your computer 6. Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Netlogon\Parameters\RequireSignOrSeal 7. In the right pane, double-click RequireSignOrSeal 8. In the Value data box, type a value of 0 and then click OK. After that, please reboot the server and then check the issue again. Regards, Xiu

Hi,I Have tried the solutions still no change. Emails will stop once the microsoft information stopped. We have restart the Micrsoft information store every time to access the email. This was happening in the middle of the night.Thanks,Michael

Hi Rajnish,I Have tried the solution you have provided and monitored. But the service- "Microsoft Exchange information store" is still stoping unexpectedly. The email won't work until we restart the service. I really need the help.Thanks,Michael.