have a pc with a DFI AM33-EL motherboard, 768 mgs of sdram, an AMD-XP 1600 processor and on board Trident video of 8 megs.board has no AGP slot so i bought a Nvidia Geforce2 MX 400 PCI card with latest Detonator drivers(41.09).also have 300 watt power supply. the problem is when trying to play Unreal Tournament or Wolfenstein the pc locks up and i have to reboot.any suggestions appreciated..