Thanks to a borked update, some PC users running AVG's free antivirus were in for a long and frustrating weekend. The virus definition update, which was released on Saturday, erroneously detected the "user32.dll" file for the Trojan Horse PSW.Banker4.APSA instead of recognizing it as a critical Windows component. Once the scanner went active, users found their AVG software recommending that they delete the quarantined file. Doing so caused systems to either stop booting or enter into a continuous reboot loop. Whoops!
The misinformed update affected both AVG 7.5 and AVG 8.0 installations on Windows XP. Vista users appear to be in the clear, though a spattering of user comments around the web have indicated otherwise. In any event, another update has corrected the error. For those who already deleted the critical system file, AVG is providing step-by-step instructions on how to restore your system back to a working state. Whether or not it restores your faith back in the program is another question altogether.
Hit the jump and let us know what security software you're using.