There's really no way it could be a virus.
I hate to be the barer of bad news, but you might have damaged part of the chipset while installing your card. Static electricity is the bane of computer internals, and you might not even realize something happened. It could be any number of things.
It would make sense because if something got zapped, there'd be a break in the circuit and to compensate everything else would be overloading
My advice is to make sure you setup a workstation on a glass table, or on the kitchen floor, away from any rugs. Remove the card, put everything back the way it was (Really carefully)...perform a system restore to a previous time and see if your computer works again. Be as careful as possible putting the computer back the way it was, and if it works once you restore it, make sure to be as equally as careful installing the video card.
If you perform the restore, and things still aren't working properly, something might have been damaged.