Problems with nVidia drivers

[G-Love]

All,

Recently upgraded my system to FC2.  I've got a dual-head card in my box 
(eVga GeForce4 MX440 SE) and I'd like to use Twinview with it.  Ok, 
simple enough.  Surf on over to nVidia, download the drivers, play with 
the xorg.conf and boom - all done, right? Wrong.  After installing the 
nVidia drivers, I decided to see if they worked properly without 
enabling any of the Twinview stuff.  Well, all went well.  Booted up ok, 
X started up beautifually, and logged in without a hitch.  So I made 
some mods to me xorg.conf and rebooted my X server at which point my 
machine totally bombed.  Screen locked, keyboard was useless, and 
eventually I had to do a hard reboot.  Has anyone else seen or heard of 
this behavior, and, if so, is it a hardware configuration issue, an 
nVidia/fedora issue, nVidia/2.6.x issue, or other?  I've been successful 
in getting Twinview to work on other machines, but with different video 
card/monitor combos.

Any insight would be appreciated.

              -greg