system lockup

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video card: GeForce4 MX 440
IRQ: 3
Video BIOS: 04.17.00.24.00
driver : Linux IA32 Version 1.0-4349
X version: XFree86 4.1.0-16 (debian package)
distribution : Debian stable (woody) (just official packages, no stuff
from testing/unstable)
kernel : compiled from kernel-source-2.4.18 + kernel-patch-preempt-2.4
(stables debian packages)
compiler: gcc version 2.95.4 20011002 (Debian prerelease) (same
compiler used for kernel compilation and nvidia driver
compilation)
Processor: AMD Athlon
cpu MHz: 1200
motherboard: MSI K7T PRO2 VER:1 N1996

Problem : I can start X without problem, but the system lockup after a while. This always append when I play OpenGL games (NeverWinter Nights for exemple), but it append also when I work normally. I suppose this is not an opengl/glx problem. When the system freeze, the screen is black and sometime the screen (not the operation system) display "frequency overange" or "DPMS OFF MODE". The system does not respond, even if I try to log from another computer by telnet or ssh. I have tried with agpgart/nvagp/none and see no difference. Also tried different kernel configuration and again no difference.

I have now absolutely no idea on how to proceed and any advice would be
very welcome.

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my config in attchmnt

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I hope the new driver will fix that problem ...

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Installed kernel 2.4.20 and lastest driver, but the system lockup problem is not solved ...