Pop ups :(

I have used Adaware to stop this on the PCs of 2 friends so far this year (pop round for a new year visit, and "while ya here... the PC is doing summat...").
http://lavasoft.element5.com/software/adaware/

 

As Custodian says, AdAware is good. Spybot is another good program which does the same thing. Try either one, or both if you're feeling especially safety-conscious.

 

It may be the messenger service that pops up. If it's still happening try blocking ports 135,137, 138 (UDP) and 135, 139, 445 (TCP). I think there's another higher up as well.

You can also disable it by doing this.

 

My brother had this. We eventually killed the process by elimination. If the ad-busting programs don't get it then I'll find the name of the process (it was "win<something>". I'll get in touch with my brother and see if he can remember the name of it. A sneaky bugger it was.

EDIT~
Here we are: WinServ Information. That should sort you out

 

remember that not all popups are evil, imagine photo galerys etc. i seen a site where the menu was in a popup once.
greets

 

While that is true, the phrase "Pop Ups" is taken to refer to advertisments/undesirables. Website features although technically 'popping up' aren't covered by this expression.

In all fairness, features such as the one you describe will cease soon. With pop up blocking now a standard feature in both the quality browsers - and coming soon to IE as well - most webdesigners wont bother with the hassle of having to instruct people to add their site to the whitelist and will adopt for conventional navigation methods. In fairness, with CSS toys to play with, there's a lot of scope for "fancy" navigation without having to mess with popup windows.

 

Check if the "WinServ" process is running when they pop up. Kill it through task manager and see if they stop.

Although I'm pretty sure that WinServ will be your answer, I can't believe it's the only one to try and pull off this trick.