LinuxQuestions.org - Ubuntu 6.10 randomly freezing on Compaq Evo

I have a Compaq Evo n1000c (P4, 256mb ram, ATI Radeon 7500) that I installed Ubuntu on. Everything runs great, but for some reason Ubuntu keeps on freezing. When it freezes all HD activity stops, my mouse and keyboard don't do anything, and the last image stays on the screen. The only way to get out of it is to hold down the power button to hard reboot.

I can pretty much be doing anything when it freezes, ie. surfing the net, listening to mp3s, etc. It seems completely random.

However, I found a way to get the problem to occur on demand. Anytime I try to run GTK-Gnutella, the system freezes. This is the only application I've found that will cause it to freeze each and every time. All other times, as I said, are at random times.

Any suggestions? I finally decided to give linux a try after bad experiences in the past... now I'm thinking about going back to Windows. I thought linux was supposed to be uber-stable? Why is my XP install more reliable?