I am running SBS 2003 and just had a strange thing happen. My outlook clients stating having trouble seeing the Exchange server. I checked the server and found the Mad.exe process was taking up 100% cpu. The CPU usage retruned to normal but my clients still could not communicate with the server. I rebooted the serve and it appears to have fixed the problem. Any ideas on what happened and what I can do to prevent it form happing again?

The System Attendant is the mad.exe process. W/o knowing more, it would be impossible to know what caused it to spike. I would ensure you are running the latest SPs and rollups for Exchange and run ExBpa against the server as well. Anything in the event logs that may give a clue?

Check the networking settings as per below link.... http://social.technet.microsoft.com/forums/en-US/exchangesvrgeneral/thread/63f8ceee-6769-4471-a46d-c2efa9d55700/ If everything looks good, may be you need to take Perfmon (for all exchange and OS related counters) and Hang dump of Mad.exe and contact PSS.

Does the Mad.exe process still consume most of CPU usage after restarting the server? If the issue persists, you can install the Service Pack and updates as Andy mentioned. If the issue persists, I recommended you refer to the following article to troubleshoot the issue. http://technet.microsoft.com/en-us/library/bb124173(EXCHG.65).aspx http://support.microsoft.com/kb/331796 Hope this helps. Novak Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.