I'm using Firefox v30 on WIN 7 Pro right now with no issues at all.
Is Firefox v30 working normally on other sites, but not on this forum? If so, then clear out your old cache and cookies, and see if the forums are working normally?
If all websites are not working, then it could be due to a corrupt Firefox profile. Did you ever back this up? I have mine setup to auto backup Firefox profile at least once a day using third party sync app.
If not, then create a new profile and see if Firefox works normally. Hold down Windows Key+R and in RUN, type or copy and paste Firefox -p and ENTER. Follow the instructions to create new profile.
Moved from Forum Technical Support