I suspect that your profile has something wrong with it, or has become corrupt as it works for the rest of the family. The profile is not deleted when you uninstall Firefox. Have you tried launching Firefox in safe made?
When installed it is an option in the Start Menu - Mozilla Firefox. If you can't find that select Run and type "C:\Program Files\Mozilla Firefox\firefox.exe" -safe-mode. The quotes are required.
You'll get a box asking you to select some resets - ignore those and continue in safe mode. If Firefox runs this probably means that some change to the tool bars, preferences or bookmarks has caused the problem. That is usually why the product hangs.
You will need to decide which things you reset – especially when it comes to bookmarks. You may need to recreate your profile, but let's try this first.
I knew this was a mistake; my grip on reality's not too good at the best of times. Glitz, in "The Ultimate Foe"