Graphics get skewered

Windows 2000 SP4 on A Dell Precision 330

from time to time the graphics tweaks out. But it only does it in the users AutoCAD 2000 s.w.
Example a square shape starts looking like a diamond. If the user restarts AutoCAD it’s fine again. I tried re-installing the graphics driver. Any suggestions before I uninstall AutoCAD competely and reinstall ?
I already re-installed thr graphics driver (to VGA and back to nVida Geforce2)