Lately when i've been on the the internet an error message pops up saying that i have performed and illegal operation. When i click ok, my browser closes (IE ver.6). After a few messages i shut down my computer. The next day when i turned it on my desktop background was gone and there was a message in the background saying that my active desktop had been shutdown. So i reactivated it by clicking on a help link. My mom ran a virus scan without me knowing and AVG Virus Scan found a .BAT extension file that was located in

I read up a little on BAT files extension a i learned that they represent a DOS batch file, a text file made up of a string of DOS commands that run in sequence when the batch file is executed. I'm not sure if this file has been opened but i think it might have done some damage to my PC.

Any advice? Plz respond.