Firefox, Flash and WordPress

Hi,

I’ve reinstalled windows and the lot on my PC, including – of course – Firefox. If I open any WordPress pop-up (theme preview, lightbox images,…) it takes forever to load.

I know it’s not a WordPress issue, since it occurs on multiple sites and NOT in other browsers. But maybe any of you experienced the same and found a solution.

Any ideas? Do I need to update anything to get Firefox as it used to work? Something wrong with Flash? I just installed the flash player.

Thanks!