Is there any way to chase down lockups and runaway load averages?

Every so often (pretty randomly) I'll get my load average spike up over 5 usually to around 10-15 and sometimes as high as 75 (dual core machine), and cause my system to lock for an indeterminate amount of time.

The only thing I can possibly chase it to is using nVidia fakeraid (RAID-1) with JFS on top of that for my /home partition.

Also I noticed that when my load averages spike, the power management system doesn't step up my processor speed from 1.6 to its maximum 2.13Ghz clock speed (not sure if this makes a huge difference with this problem).

Any ideas?