What's up with Firefox and "pop up windows"

I’m a long-time user of Firefox and really appreciate it’s ability to block pop-ups. But I notice that recently it is creating new instances(?) with pages/sites I did not select. It’s as though I right-clicked on a link and selected Open in New Window – except the window is stripped down, doesn’t include the menu bar, toolbar, any of the other stuff that’s normally at the top of the screen.

Is there something else that needs to be turned on to stop this annoying behavior?

Sounds like malware to me. Get Malwarebytes and clean your computer.

One thing to check is to make sure it’s actually a firefox window that is coming up. If it really is coming from firefox it will have the little firefox logo at the top of the window, even if the rest of the stuff (menu bar, etc) isn’t there.

Malware, as Leaffan suggested, is also a definite possibility.

Another possibility is that a pop-up window was spawned when you clicked on something or pressed a key for something. Firefox intentionally doesn’t block these types of pop-ups because that would prevent a lot of websites from working. I don’t have a lot of experience with them, but there are add-ons for firefox that you can use to block these (adblock plus pop-up addon, for example).

If the pop-up windows are all coming from a particular site, you can block that site with an add-on called BlockSite.

Could be legit. The site I use to check TV times opens a 'stripped down) page if you click on any TV program listing for further details.

I’m running the latest version, 3.6.13. and have no such problem. Of course I also run “no script” that eliminates some things. Maybe you should try that.

It seems every new version of Firefox comes with some bugs. The current one will stop the scroll function sometimes or develop a jumpy page.

You aren’t running the beta, are you? Firefox 4.0b7 will do this on some sites. It has to do with the new Javascript engine, and certain scripts that load a page within a frame. Firefox misses the frame.

Malware is more likely to take you to some random site, so if you are running Firefox 3.6.13, I’d just create a new profile.