Gaming Graphics Issues

[Ryle]

I know the following issues may seem similar to other threads but I am new and not sure if this is a documented problem or not.

When I play certain games (NWN native or Diablo II through Cedega) the game works ok but every couple of mins the screen freezes (there is usually some graphics distortion here as well, like a layer or two disappearing). I can still hear the sound so I know the game is still running ok. I can clear up the issue by hitting ctrl-alt-f1 then ctrl-alt-f7 to switch to the console and back. This brings back the screen until the problem happens again.

I got a similar issue when running Doom 3 through Cedega. Everyone 30 secs or so the lighting would mess up. I could still see the lights themselves but they did not illuminate their surroundings. Everything was really dark except for the actual lights. Again, switching to the console and back would clear up this problem. I was actually able to fix this problem by changing the ingame renderer from NV20 to NV10. I was able to play the game for quite awhile (it eventually did freeze but I don't know if this was related).

Finally I have been having freezing issues with xscreensaver. If I leave it on for any length of time eventually it will freeze and even lock the keyboard so I can't try the console trick. I don't know if this is related but I think with the other problems I've been having it sounds suspicious.

So I've read in these forums that freezing has been an issue. Are my problems part of this or not? How should I go about debugging whats happening?

My Specs:
Soyo SY-KT600 Dragon Plus v1.0 mobo
1 gig pc2100 ram
NVIDIA FX 5700LE 256mb
nvidia-glx and kernel 6111 (could not get the 5336 working)
linux 2.6.7 kernel
gentoo distro running gnome 2.6.2 rc1 and xorg 6.7.0r1
Tried with both agpgart in kernel and NvAGP

ps How do I know if I am currently running agpgart or nvagp? whats the difference between the 2?