PC crashing for ALL OpenGL games

Hi all,
I have just become aware of a problem I have with OpenGL.
I discovered it when installing the Return to Castle Wolfenstein demo.
The PC crashes when the level starts, the monitor goes amber as if the refresh rate /resolution are too high. I need to power down and reboot.
I then tried to install Quake 3 to see if that would do the same ( Wolfenstein use Quake 3 engine )
Same problem - crashed again.
Then I set Unreal Tournament to run in OpenGL mode ( I normally run it in Direct3D )
This crashed too, the game will run for a while then the monitor dies and only powering off will let me back into the PC.
The problem is on my 2nd PC ,which not used as much, which is why the problem has only just come to light.
On my main PC all games run fine.

My system spec with the problem is:

Win 2k SP2
ASUS Geforce2 V7700
PIII 600
Detonator 4 drivers (also tried older drivers too )

The system spec that works is
Win 2k SP2
ASUS Geforce3 V8200
Detonator 4 drivers.

I am SURE the problem relates to the OPENGL drivers, and have tried different settings in the OpenGL config for the video card.

Can anyone help in any way? I am very confused!!!