We are using Windows Server 2003 R2 Standard x64 Edition Service Pack 2. We're running it on a dual core 2.39ghz opteron with 8 gigs of ram and 8 250gig hard drives organized in a couple of RAIDs. We have at least 100 gigs free on each array. It usually uses less than 1 gig of ram and the cpu usage idles around 10% and doesn't ever seem to go over 30% during normal usage. We're using it for Active Directory and file sharing for a small network (about 25-30 clients). This server is about 10 months old.
Everything works fine 99% of the time. However, every two or 3 weeks I will start getting complaints from several people all at once about the file sharing being slow, and then shortly after that, they will not be able to connect to the server at all. It will just time out. When this happens I log into the server and check things out and there doesn't seem to be anything weird in task manager, cpu and memory usage is normal, no errors from the RAID controller, no errors in the event log. The only thing weird is that looking in Computer Management -> System Tools -> Shared Folders -> Sessions there will be 2 or 3 users that have hundreds of open files. I know these users well and none of them really are opening hundreds of files from the server at once. Killing the sessions with several hundred open files open does nothing to revive the server. If I try to stop or restart the Server service, it times out when stopping, then it's stuck there. It just hangs on stopping forever, and I have to completely reboot the server to get everything back.
I haven't been able to find any information on what could be causing this and I'm at a loss. Any help would be very much appreciated.