If you really want to use Firefox and have not been able to use it I found a way! Took me a week lol.
1> Go to Firefox Options > Advanced
2> Check Never check for updates
3> Uninstall Firefox
4> In another browser go to
Download Firefox 38.0.1 - FileHippo.com
5> Click on the download button that says download this version 37.79MB
6> Download
7> When prompted Choose Custom settings
8> When you are prompted do not accept the maintenance service.
9> install and launch
Note: You may have to uninstall Arcadeox before doing this. "I Did" You will be prompted to download it again.
Hope this helps!