Some virus' are really nasty. Even though you may be able to clean that one, it could very well popup again from another file. I've had one such virus that even after cleaning, it popped back up in the next reboot, time and time again, it was a sick & frustrating 6 hours I spent on that merry-go-round. Eventually, I caved in, reformatted & reloaded. My son is about to experience the same thing; his pc (not using Avast, using Norton), recently got infected -- Avast is going on his clean install when he finishes. I restricted him from IP access until the reinstall is done