I had the same problem (vimax ads on 70% of the web sites I vist) and even my antivirus Antivir and SpyBot couldn't find anything and I could only update both manually. About a month after these ads started appearing I kept getting Warnings about a virus from Antivir, and no matter what I did the Warnings kept appearing.
Then my friend gave me a program called ComboFix and it worked really great (I have Vista 32 bit).
Now the ads are gone, Antivir and SpyBot update themselves flawlessly. Perfect. I can't provide a link right now, so you'll have to google it yourself.
And yes, I realize this thread is old, but since I couldn't find a solution myself on the Internet, I figured I'd post what worked for me here, one of the first sites that came up googling for "vimax pop ups".
My guess is that that virus replaces the usual ads with ads from Vimax.
Here's a link for ComboFix
http://www.combofix.org/
You should disable any Firewalls and/or antivirus programs while using ComboFix. And I can tell you, even though I once had still my antivirus running and the other time I closed ComboFix before it was done, I didn't get any problems, so don't worry too much. But in the rare case that something goes wrong, please don't sue me.
