windows 2000 server and Exchange server not accessible

[cY2k]

For some reason, our Exchange server (running windows 2000 server) has become inaccessible from other computers on the network. If you go to My Network Places, you can see it listed there, but when you try to open it, it says its not accessible. I've tried it from multiple computers it doesn't work from any of them.

Also, since its our Exchange server, we can't open Outlook from our workstations and check email. It's as if the server is not on. This is so strange... and on top of that, when I checked out the server itself, it seems to be running really slow, every operation you try to do takes much longer than normal (clicking the Start button, opening My Computer, opening My Network Places, etc.) What gives?

 

[Davetoo]

What do the event logs say?

Have you checked for virus activity?

Have you tried rebooting the server?

I'm Certifiable, not certified.
It just means my answers are from experience, not a book.

 

[cY2k]

Event Logs: Nothing out of the ordinary there.
Virus Activity: I'm running a scan right now...
Reboot: Yes, tried it. This has actually happened before, maybe twice now. I've rebooted each time, which fixes it for a while, only to have it happen again a few days later.