See if you can remove an AV program of choice from there. Other safe mode options include "system restore" if need be.
The problem is this : with AVG being already installed, Panda was, too, installed and after a reboot a message appeared that went along the lines that if the message appears for the first time, PC should be restarted again. After the restart, the message with similiar content appeared again, saying that in order to prevent damage PC has shut down (or won't let to log in), and that the hard drive should be checked for viruses. I'm assuming the cause was the second installation, since no other changes to the PC were made at that time. The details are scetchy, since it happened to my mother in the other city and she's asking me what should she do and what can be done about it. Help, anyone?