Software Raid clogs system?

Got a Centos 4 (fully updated) system using software Raid that works fine after reboot for a couple hours (or less) and then the load average goes to above 30 and the machine crawls to where no one can access it (email is application). top commands (when they respond) show large percentage of wait time, but don't show any particular process chewing up CPU or memory. Number of tasks is not out of the ordinary either. Not even using swap as it has 2GB memory.

2-500GB eIDE drives with a 40GB boot drive that has the OS.

Rebooting resets the whole thing and it repeats some time later.

Any ideas?

At this point, I'm headed toward a single data drive without the raid to subtract out the possibility that raid is causing this.