I'm running Windows XP SP3. My browser is IE8 and I keep my computer fully patched.
The malware started out as Antivirus System Pro which is a scareware program that tries to bully you into paying for their software. I was able to clean it with malwarebytes but was left with annoying redirects and popups in IE.
dolfanmark, I ended up using Combofix but only as a last resort and found out it was actually a rootkit disguised as my cdrom driver which explains why it went unnoticed by all the other cleaners I tried. I suggest you go to techsupportforum.com or bleepingcomputer.com and follow instructions to get help before trying combofix as it can leave your computer inoperable....don't ask how I know.
Hope this helps.