PC keep rebooting

Hi, I have this PC that keep rebooting every now and then. The error message is :
Kmode_Exception_Not_Handled,Address A004B005 base at A0000000, Datastamp 3cdb4146-win32k.sys or ntoskrnl.exe

I suspected that it might be due to some conflicts with some driver. All devices (NIC, VGA card) are built onboard (Gigabyte 845GL). The spec of my PC are P4 1.7GHz with 128M RAM, running on WIN2K. Any help is appreciated 🙂