I've had problems with Acrobat for a long time. I see one of two things: 1) Wide dialog box with no message, just an OK button. Refresh the page and this goes away. 2) Small dialog box prompting me to select a language; has OK and cancel buttons. Doesn't matter what gets clicked, some dialog that I can't see becomes modal forcing me to kill the FF process and reopen it.
For IE tab, grab
Coral IE tab. If you don't want that, download the .xpi file for the regular IE tab, rename .xpi to .zip, open that one file and change maxversion to 3.6 and it'll probably install fine.