I have been experiencing an odd problem lately on one of my exchange servers. At 5:00 PM every night the server slows to the point it hangs for 15 min to an hour. The available memory dives from 2.2GB down to 500MB or lower, but no processes in the task manager have memory usage going up. The store.exe actually goes down in memory usage during this time. The CPU usage stays normal.
The only errors I can find during this time are Event ID 3007 & 3014. They are the "Server ActiveSync" and only show up for users that have phones that connect to their mailboxes. I believe these errors are just a result of it locking up and not related to the actual problem, but Im not sure.
The server has Windows Server 2003 R2 w/ Exchange 2003. it is also the file server for about 10 computers that are located at the same site. The two other servers at that site work fine during the "slowdown", one is a database\sql server and the other is a terminal server that is used by few people.
Any help would be much appreciated.