Turn off all power management features in the control panel. Also Xolox seems to grab huge chunks of system resources periodically, if you don't have enough available it will hang your OS.

Make sure you've got at least 75% system resources available. If not use Ctrl Alt Delete to close down anything running in the background that you aren't using (like CDr software, seti@home, etc). The number of downloads going might affect this I'm not sure.

Finally it doesn't seem to like being left on the downloads screen so before you go to bed change it to the search screen.

Worked for me, good luck.
Mart