Mac Book Pro cursor freezes

Two days ago, I tried to transfer data from an external USB RAID to a solid-state USB flash drive. The transfer crashed my MacBook Pro, and I had to stop and restart the machine to continue.

Since then my external USB wireless trackball will work for about two minutes, and it then begins dying. The movements become significantly less responsive (more jerky), the clicks are more seldom accepted, and eventually, the cursor becomes completely unresponsive, and will neither move nor accept button input.

Turning off the trackball, and then restarting it usually "fixes" the problem, but within two minutes, the trackball is in its death spiral again.

The touch-pad on the MacBook Pro does not seem to be affected.

I've tried rebooting the MBP with the shift-control-option keys depressed to clear the MBP's cache, but this problem persists.

What must I do to restore normal function?

Boomzilla