Firefox Help Please.

Hi folks
Had trouble following new install of CIS, could not get av engine verified, so did a complete uninstall including reg edit and downloaded and installed again. The problem I now have is that I use a second monitor and whereas previously I could have a Firefox page open on both screens or as many new pages as I required, now I can only open 1. I can however open an IE page, but why should I have to? Am I missing something?

Problem solved, it was a FF toolbar add on, disabled now back to normal.