Hi shughes3,

Does this happen with all sites or just on a particular one? It might just that the website is in a "bad neighborhood" so to speak. Do you have the Pop-up blocker settings, exceptions and troubleshooting enabled in Firefox? That article will show you how to turn on the pop-up blocker and how to manage it as well. You might also want to take a look at Troubleshoot Firefox issues caused by malware although it sounds like you've got that pretty well covered.

It happens on many different sites and the pop-up blocker is enabled. I'm at a loss.