Having problem with Panda Antivirus Platinum

Lst nite (03/20/05) my nephew downloaded and intalled Panda Antivirus Platinum trial version on my computer and after that the computer is frozen. They tried to un-install it but they can't, then called me for help. However I can't do anything because it keeps giving me freezing screen. After I restarted, the comp will work for a few second then freeze again. I want to RESTORE my comp in hope that it can get rid of this problem, but since it's freeze, I can't do anything. ANybody in here ever intalled this software before? Do you have any problem and know how to solve it? Please let me know. Thanks
I am really appreciate any help.