Okay... Now that we know you know how to get into safe mode etc I still think it likely that within the BIOS (CMOS) setup someone enabled the virus protection option. Reboot your computer and carefully watch what it says as it starts up. It will probably show you the motherboard brand and model along with displaying some, possibly very quick, message about pressing a certain key or keys to enter setup. I need you to find this step first before we can progress. Alternatively if you write down the model number of the motherboard / bios for me I'll look it up somewhere.

Ingmar

(You learn patience when lying on a book shelf for 10 hours on a surveillance job!)