When you are trying to update AVG antivirus version 8.0.x you might
see similar to the following error

Invalid Update Control CTF File

*Solution 1*
I have found the solution from AVG forums

You need to rename/remove the CTF temp files in Cocuments and
SettingsAll UsersApplication DataAvg8updatedownload…. Dont delete
all the .bin files in there unless you want to re-run all updates
since your original installation (reinstallation seems to cause a
problem in IEs Link Scanner which causes IE to Crash). Only
rename/remove the avginfo files that end with .ctf

For Windows Vista users

Go to the following location

CrogramDataavg8updatedownload

Delete the following 2 files

avginfoavi.ctf and avginfowin.ctf

*Solution 2*
You can also download and install AVG Mechanic from here

Read more : http://www.get4today.com/virus/fix-for-invalid-update-control-ctf-file-error-avg-anti-virus-update/