i seem to have some strange type of ad-ware on my pc. at random times (about every 3-10 minutes) another browser window opens up with ad in it. it opens up by itself.
i tried running spybot and zonealarm but it didnt fix the problem
any idea what it might be?

If you try going to one of the spyware forums - I can't think of any names off hand - they can show you how to set up hijack this to scan your PC and see if it can find any suspicious files, then they will walk you through what you need to do to get rid of it.

It sounds like a variant of Vundo, or maybe you picked up xrun or something like that, I know a few weeks ago that was dropping files that not many AVs were recognising. Or it could be CW adware, but I'm not very knowledgeable in this area and the description fits almost all adware. I think you'd be better off in a specialist forum where they can help you isolate the file and clean it.

I agree that's your best option. This forum is reliable, safe and very helpful: http://www.bluetack.co.uk/forums/index.php?showforum=172

thanks for your help, will check that out later