Since you're experiencing the problems in both browsers, the problem is most likely not related to firefox so there is no need to try re-installing it. What you should try doing is uninstalling both Adobe Flash Player ( or related items ) as well as Java related items and try Re-installing them. Just go to:
Start->Control Panel->Add or Remove Programs
and for all the items that start with "Adobe Flash Player" or "Java", click on them and then click the "Remove" button that appears. Then restart your computer if necessary.
Now, you'll want to re-install them. Download and install Java from here:
and Adobe Flash from here:
After you've completed, test the websites again in both Firefox and Internet Explorer and post back.
It's always nice to have some feed back after things are fixed =)