Reset the BIOS by shorting out the pins on the motherboard with the jumper. It's normally the jumper closest to the BIOS battery. With your computer turned off, connect the jumper so the pins are connected, then apply the power to the computer and turn on for a few seconds and this will completely reset all of the values in the BIOS to factory state. Turn off the computer and disconnect the power and put the jumper back to its original position. Now try and start your machine and install windows or whatever it is that you want to do. e2a: I think nHancer has messed up some of your memory voltages or timings in the BIOS or possibly some other system critical setting.