A cousin of Redhat rendering similar issues with me too
I also face similar problems but not that serious as raaki mentioned above. I am using Mandriva with intel i810 drivers on 865 chipset. With 2007 it all went right then I tried Debian it was just fine. Later using spring I got this trouble. the greeter opens with a resolution like 640X480. Then the desktop too the same. I have to change it then. I learnt earlier and the 2007 installation itself suggested using i915resolution. That was for Mandriva with Intel.
Redhat with Nvidia...!!!??
got to do some working on that...