You can rename the AVG program folder from the command prompt. Then boot normally and run the repair installation of AVG.
See for example an excellent description here http://forums.avg.com/ww-en/avg-free-forum?sec=thread&act=show&id=132969#post_132969 by Pulse21
I am trying to remain calm but it's getting harder and harder. I have lost my main PC since Friday AM due to the bad AVG update like thousands of others.
I have been all day on the AVG forum and now they seem to be down, I don't know why, I tried to access them on 2 other non infected PC's to no avail.
Ok enough of the rant I was wondering if someone would have a final idea before I put my Windows 7 DVD in there and restore to factory new and lose my stuff (I back up but still stuff gets lost).
I have done the following:
-Create an AVG USB boot disk which failed (I went into my bios and boot order and I don't see a USB boot option only DVD and HD.My PC is 1 year old AMD Phenom II, I am surprised I don't have that option.
-So I tried to create an AVG bootable DVD with their .ISO file which I got done, I checked the file was burned on it and it is there.I made sure to change the boot order in my PC and put the DVD first. That failed, I tried 4 times.
-I have rebooted my infected PC probably 50 times in the last 2 days and have hit various F keys to no avail.F8, F3, F12,F11 and the ESC key to no avail.
-I can't enter safe mode, tried countless times, it brings me to the startup repair utility.
-Startup repair will not work, it fails to restore to an earlier date.
-The only 2 things that I know I haven't done yet are:
1)Use my windows 7 DVD to do a fresh install of windows (My last resort if this post fails to help me.)
2)Do anything from the command prompt which I can access. Guys is there anything I can type at the command prompt to help me?
I appreciate the help.
(Logging off now and going to try to relax in front of the TV with a scotch on ice.)