pc hangs-p4-shuttle av40s3

after succesful installing of all components(except agp-video-card) i separated mainboard plus all components out of the case. as said: agp geforce2 mx400 did not work. we checked everything and came to the conclusion that inside the case agp is notworking. the fault was probably wrong screws(too big) and too small washer(i hope its the right word) causing wrong contact. we will see. the actual problem is: i took out all cards(beside agp which is working outside the case). then i mounted audio and network and multimedia can be seen twice in the startmenue. how can i erase all entrees in bios? i thought activate configuration will solve the problem. pc hangs. or should i wait more minutes not just 30 seconds? i tried out all bios options(default and minimum)