By DAT files i do mean the virus definitions. Some people get norton, dont pay for the subscription, never update, BUT wonder why they get viruses and CLAIM Norton doesnt work. Since this does not apply to you i would say try the second approach.

To boot in safe mode you normally have to hit F8,F*0, or F*2 on the boot screen. Since you cant see the Boot screen i would recommend getting the right video card for you computer because this could be causing some functional issues with windows.

The registry values that should not be there are sometimes very obvious. If you see BritneySpearsPornXXX.exe it doesnt belong in your startup (Unless of corse you put it there ). My best recommendation is to clear everything out of your startup registry values and msconfig startup. After you do this, go back and add the programs you want to run. This way you eliminate the possibility of a program key being spoofed.

Hope i've cleared things up a bit