Just a few days ago I built a computer for someone. I gave it an Abit NF7-S2 motherboard and ATI 9800 Pro 256MB graphics card. For some odd reason, when I change the AGP aperature to 256MB in the bios, the computer refuses to start up after I save and exit from the BIOS. The computer doesn't display anything and beeps (I don't know the exact number of seconds). I have searched on the forums for this problem and found the same thing has happened to someone else, however, it didn't happen as a result of a change in the AGP aperature. Does anyone know any way to fix this problem?