Don't you love hardware autodetection?  It makes life so much easier...

A couple of things you can try:  Look to see if RedHat's hardware "wizard" - I 
think it's "Anaconda" - made backups of the XF86Config file - /etc/X11/
XF86Config.  Look for text-based configuration tools to re-write the file - I 
don't remember what RH is calling theirs now, but look for binaries that 
begin with "x" and have "cfg" or "config" in the name.

It sounds like there's a pretty serious hardware conflict in your system.  I 
would check for a BIOS update, and run any BIOS hardware detection/
configuration routines to see if that helps at all.  Check any settings there 
to make sure they make sense for your hardware.