This is relating to my previous post, Does HTNet Crash Your Firefox 1.5?… I found out that the problem wasn’t related to any of the things I listed in that post. The real culprit is: NVidia Linux Graphics Driver.
As soon as I updated from build 7676 to the latest build (8178 was the version I upgraded to), the problem was fixed. No more X hang ups for me… Yay! Hopefully this might help somebody else out there.