Dear all. I have an Exchange Server 2007 Server rollup 5 with CAS, Mailbox, Hub roles installed. and every 1 hour it restart automatically. Everything goes fine and then it just restart. The event viewer shows "The previous system shutdown at ....on ... was unexpected" Any ideas?

Hi, Do you get any error in event log? Basically check if it is restarting with any bug checkthen you may find the cause of reboot based on that. If no error then I would start with hardware diagnostic checking because faulty hardware or driver may cause unexpected shutdown. I would also update the drivers of hardware if any latest available on vendor site.

Hi, First please try to uninstall Rollup 5 to narrow down the root cause. If the problem still persists, then we suspect that it could be the OS related issue. I found the KB 894278,it give solutions which would be applicable to this issue. The computer may automatically restart, or you may receive a "serious error" message or a Stop error message in Windows Server 2003, in Windows XP, or in Windows 2000 http://support.microsoft.com/kb/894278 BTW, what is your operation system? What is the version of your Exchange? Exchange 2007 with sp1? Is there any other application installed on the Exchange Server? Hope it helps. Xiu

No error in the event log, it was a hardware problem, i changed the power supply and now it works perfectly. thanks Amit for the advice.