Ok, as Nforce 4 is still relatively new, not really much I know about those at the moment and there probably isn't much in the way of new drivers to update to.
With regards to your 6600, what level of driver are you running? If you have the latest installed, try rolling back to a much earlier version.
Increase the AGP Aperture Size to double the limit of your Graphics Card and try turning off AGP Fast Write.
You should also run the driver Cleaner between uninstall and reinstall. Both Cleaner and drivers can be obtained from
www.guru3d.com
One last thing to try, and this may sound a little strange, but it has caused me a few problems with Guild Wars over the last week. It isn't related to graphics, but one process after GW shuts down sits there at 100% CPU usage. I can't shut it down, and a soft reboot doesn;t work either. As I reboot, the same process starts running at 100% again. I have to switch off and then reboot.
So, the file is part of my Zone Labs Security Suite and I keep getting errors from Microsofts .Net Broadcast software. So, I decided to completely remove .Net Software.
The only reason I say this, is because Guild Wars is the only piece of software I have installed and updated recently and the last few updates is when this problem started. So, I would suggest trying a full uninstall of .Net Software and see if this helps at all.
It's a long shot, but it's the only thing I have had go wrong on my machine in the last few major Guild Wars updates.
At the end of the day, only try one of these solutions at a time so you know which one works best or works at all in any way.
This will help others that have similar problems when you post it back here.
