Opanda iexif works fine on my FF 3.5.1 Click Here its freeware
Seacrh for 'exif' in the add ons, there is an Exif viewer that works with 3.5 though slightly different from the version you are probsbly used to
Might just have to go back to the old version of Firefox:shrug:
Thats exactly what ive just done, dont know if it was me or not but 3.5 just didnt seem right, not only that, nearly all the plug ins, add ons and themes I have didnt work with it.