Hello I'm running a windows 2003 small business server. Recently there have been problems with exchange - for some reason the service freezes and the store becomes unavilable. I cant find anything in the event logs that could cause this. It seems to happen when some users log onto the domain. When the server is restarted exchange works normally again. What could cause this? Any help appriciated.

If you don't have any events that coincide with the error, I'd recommend running ExBPA and see if it can pinpoint any problems. If everything comes back clean, please post back to the group. Get ExBPA here: http://technet.microsoft.com/en-us/exchange/2003/bb288481.aspx