Definately do not back anything up yet - you are likely to reinfect if a bad file is backed-up (you won't know till it happens). Doubly definately don't copy anything to another machine. Lots of virus software is able to reproduce after being 'cleaned' as the exe files can be disguised to read like a normal operating system file, so your symptoms are not unusual. It is likely that AVG can spot it but can't cleanse tyour system properly. If you have windows, try Microsoft's Malicious Software Removal Tool, which you can download. Checking the name of the infection is sound advice, there are often tools available to remove specific infections, but use a reptable site.