Locked out of safe mode, by trojan?

My father's computer was severely messed up and he asked if I could fix it. I used adaware and spybot to take care of most of that junk, but a real problem came when I used symantec antivirus to try and clear up any virus'. There ended up being about 10-15, the two types I remember were Trojan.dropper, and Trojan.alwayup. It said that it could repair or quarantine them, access denied. So I followed the symantec website's recommendation to restart in safe mode and try running the scan again. I followed the instructions to run "msconfig" from the "run" menu and selected "safe mode" in the reboot. But when I restarted the computer, my father's password wouldn't be accepted on the windows login. I called tech support and they had nothing to say except reformat. The problem here lies in that, because I checked the box in "msconfig", even if I hit F8 during start up and tell it to restart in normal mode, it still starts up in safe mode. Is anyone familiar with any virus' that change the login passwords? My father's computer is as follows:
Panasonic Toughbook CF-W2
runs Windows XP Professional
60GB HDD
512MB SDRAM(DDR)
Intel Pentium M Processor 753 ULV
1.2 GHz
2MB L2 Cache
400MHz FSB

Thanks for any help you can give