First, AVG is simply a virus scanner. It doesn't try to do everything like McAfee and Norton have begun doing lately. That's why, IMO, it's good at not consuming huge amounts of resources on your system. It's not going to pick up spyware no matter how many times you scan for it.
Second, whatever you think the cause is, the reality is that Internet Explorer is targeted almost exclusively for this sort of thing. So it would stand to good reason, that not using Internet Explorer, or any Internet Explorer based browser, would be very beneficial. Making the switch to Firefox, Opera or Seamonkey would go a long ways to preventing this sort of thing in the future.
Third, Google (or your search engine of choice) can be an invaluable asset for dealing with this sort of thing. I'd wager a search of "winfixer removal" would turn up many useful pages.
Fourth, have you tried scanning your system in Safe Mode, with System Restore turned off? This is generally the only option for getting rid of some of the more persistent pests
Fifth, if all else fails, download and run a copy of Hijack This, and then post the log over in the virus and security forum. Just be kind, and clearly label the subject, so people who don't want to look at your log can skip over it. If there's something anomalous, someone will likely find it, and assist you in expunging it from your system.
Once you get everything cleared up, you'll want to revisit point #2. Ultimately it's your choice, but I know what I would do/have done. Weighing the time and effort required to acclimate yourself to a new browser against having the ever present threat of repeat performances like this one, with a strong possibility of increasing severity over time, makes for a pretty tipped scale to my way of thinking.
OK...I need some help. I'm running XP Home Edition on an HP home PC. I keep getting warning notifications that my computer has been infected with the "Blackworm Virus." I am then routed to a WinFixer purchase website (I haven't purchased or installed anything). In addition, there seems to be some other "bug" that will takeover my browser and route them to other sites. I have run AVG, Microsoft Spyware, Spybot S&D, Ad-Aware 6.0, and XoftSpy Scan - all to no avail. Spybot S&D, Ad-Aware and XoftSpy detect the cookies and allow for immunization but this action is obviously not getting to the heart of the problem. AVG hasn't even identified the items. I have also tried de-activating the restore points and rebooting in safe mode but - I don't know specifically where to look for the executable of these annoying pests or what exactly I'm looking for - so I have been unable to find anything. Does anyone have a suggestion or a fix for my problem? Please help - I'm getting to the point where I'm seriously contemplating scrubbing the drive because I don't know what else to do to free my system of this problem. Thanks.