AVG isn't downloading. It's just saying "run as" then stops. :c
Problem.
This means that your virus is likely preventing it from running. This suggests a serious virus, possibly polymorphic, but not necessarily.
I'd suggest either of two things:
ONE:Try partitioning your drive (With a tiny disk space. Install XP or something
tiny.) and then installing Avast!, as it can do boot time scans. Do a boot time scan, say, three times. Avast! is reliable, and I use it in tandem with AVG.
Once that cleans it all up, use AVG on it from inside the new partition, this should take an hour or so.
Now reboot, repair your old partition with your Windows CD and log in, then delete the new partition and enjoy.
Whatever you do:
-Don't access ANYTHING off your old partition through the new one. No sense in contaminating it with virus.
Don't do so much as look into it.
-If it is a polymorphic virus, which can be found by googling the name of the virus Avast! reports, then consider your programs lost. I had one, and polymorphics attach themselves into programs you run since you acquire one, so Windows and a couple of other programs get written off. Be prepared to reinstall some things.
-If it isn't a polymorphic virus, you are lucky. It is, however, still quite destructive, as if a programmer has gone to the trouble of protecting it against any direct anti-virus tools, then it is a well equipped program.
-If you have Vista, turn on UAC (user access control) when you get back into the main partition, and set it to maximum detection. Yes, its a pain in the ass but it may just protect you while you clean up. Turn it off after a couple more scans by whatever software you end up choosing, proprietary or non. It should ensure nothing you don't want to will run.
TWO:If you don't have the space for a partition, I would gather all your documents and important stuff onto a thumb drive. Consider this device infected. Now I would take it to a Macintosh, take everything off,
format the disk and then get something to take care of infected Windows content on a Mac, such as ClamXav. Scan your files and then format your PC. After this is done, reinstall Windows and transfer what files are considered safe back from the Mac to your PC.
This, naturally, requires a Mac, where PC viruses are harmless.
DO NOT DO IT ON ANOTHER PC.
