X windows problem

I recently built an Intel Dual Core (2140) system with 1G of RAM. I
installed RHEL5 and for the most part everything is running great. I
use this box mostly to run Azureus and as a big file server on my home
network.

Normally, when Azureus just runs this computer stays up no problem. For
some reason, especially during heavy ftp file transfers, X will lock up
the computer. I'm running vsftp as the ftp server BTW. I can ssh in
and see that the X process is taking 99% of CPU time but using its
normal amount of memory. I can tool around in ssh but can't do a
shutdown -r now. Trying to kill the X process is unsuccessful as well
meaning I have to do a hard reset. I can't get into any of the console
windows either using Ctrl-Alt-F*.

The graphics card in there is a Radeon 9600 S6. I suspect there might
be something going on with the graphic card and the OS causing X to go
into an infinite loop. I'm also running Gnome. The box is solid when X
is not running but I need X to run Azureus which runs on top of Java.
This also sometimes happens when I run Firefox too so now I'm careful as
to how long I use it on that box.

Does anyone have any idea what might be going on or know about a common
bug in RHEL5 that might be causing this? I'm just trying out RHEL5 so
I'm not an official user and can't get support from them. I'm thinking
of moving to Fedora Core 8 but am not sure if I'll run into the same
problem or if a different video card would help for that box.

If anyone has any ideas what could be going on or links to where I can
get more info that would be great.
.