I work as a Computer technician at a small company and I deal with infected computers all the time. My advice? Be patient! Disinfecting a computer can be an extremely time consuming procedure. Three working days is the norm for heavily infected machines.
Here’s what we do:
-Most computers we get are so screwed that they can only be booted from Safe Mode. So, I boot from Safe Mode and install and scan the computer with Lavasoft’s AdAware. This usually cleans the computer enough to allow normal booting.
-Then I boot normally and install Microsoft Antispyware (which cannot be installed in Safe Mode) and Spybot S&D. I then connect to the internet and update all three antispyware programs.
-If the computer doesn’t have a network card, I have to open it and install one for the purpose of downloading updates.
-Once the antispyware programs are updated I reboot the system in Safe Mode and run full system scans with all three programs. Depending on the number of files and the computer’s speed, this can easily take more than three hours.
-When these scans end and I am still in Safe Mode, I install and scan the computer with HijackThis. By now, the computer is usually 100% spyware free, but some times I need to edit the Registry by hand. For example there’s a nasty spyware that hides the Wallpaper and Active Desktop tabs from the Display Properties menu.
-Then I boot normally and I install and update an AV program, usually Grisoft AVG Free. I reboot at Safe Mode once more and perform a full scan. Again, this can take quite a lot of time.
-Finally, I install Service Pack 2 and all Windows updates from Microsoft. That’s when we can give the computer back to the customer.
This procedure can take 1-2 full days if and only if:
-All AV/antispyware software and Windows updates installs without gliches
-There are no hardware problems
-We are not too backed up with other computers
If problems of any kind occur, fixing the computer can take a week or more.