I have found a few clients recently having a problem with AVG updating and it says “Invalid Update Control CTF file.”
This should be fixed with the latest version of AVG reinstalled over the top, but if you don’t want to do that we stumbled across a little tool that does the job nicely, AVGMechanic and can be downloaded from StrategyOnline.
We can’t support the use of this tool, so if you are concerned about using it please contact your local IT support but we have found it works nicely. All it does is removes the AVG CTF files that are causing the problems and then you will be able to update.