Over the last week FireFox has stopped opening or downloading pdf files. Tried several plug-ins and nothing is working. Anyone else experiencing FireFox problems? Also.... I have to re-start FireFox on Snow Leopard a few times a day as it hangs. The pdf problem is happening on both Mountain Lion and Snow Leopard. Luckily Safari is working fine.

Maybe try Aurora and see if that works (assuming it runs on Apple).

Go to Preferences/Applications and scroll down and file .pdf/Adobe PDF Documents and select your option on right...

CRapple

Personally I'd try installing PDF-XChange.

http://www.tracker-software.com/product/pdf-xchange-viewer

Go to Preferences/Applications and scroll down and file .pdf/Adobe PDF Documents and select your option on right...

I'm not an Apple user but this looks like the way to go. I've had the same problems on Windows & went to Firefox help. It has installed it's own PDF reader which is a load of crap. So, on my Firefox it's Tools/Options/Applications & select whatever PDF reader you have installed.