OWA stops working

Server 2003 Standard Edition with SP2. Exchange 2003 with SP2.
Just started having an issue where OWA will stop responding after about 5
minutes. You can bring up the login screen, type in your username/password,
but the site will do nothing after that. Basically just sits there like it's
loading, but nothing will happen.
If you restart IIS, it will work for about another 5 minutes, then the same
thing happens. No errors are showing in the event log whatsoever.
I have tried reinstalling SP2 and a few minor things, but with no error
logs, I'm not sure where to go?
.