I have had the problem of multiple windows popping up several times too. I can't remember if they were all Curezone, or other sites. The last time it happened,it was while reading on Curezone. I never knew if it was Curezone or a bug with Internet Explorer.
I decided to download the Yahoo Toolbar and use their free Anti-Spy feature. I notice that Curezone plants a lot of Spyware cookies now. If I am here for a long time I sometimes delete them a couple of times. I don't feel all that secure with Yahoo either, but I do like keeping the tracker cookies at bay.