My url bar is indentured to right and doesn't start where it's supposed to.
When I click on the URL bar, the whole URL or whatever i type in is indentured to the right. I reinstalled Firefox and the problem was gone. But after two days the same occurred again out of nowhere.
I didnt move the extensions folder to the new profile. The prefs.js file alone was enough to make this problem occur.
I made a new profile and added the add-ons and themes to it (since i only have addblock plus and one theme), but after restarting the problem didn't occur.
None of the individual preferences jump out at me as a problem, and when I used those in a prefs.js in a new profile on Windows 7, nothing strange happened. Perhaps it is something particular to Windows 8.1 (different theme, fonts, etc.). ???
Maybe it's really just the Windows 8.1 setup.
I copied the prefs.js file from the faulty profile to the new profile i made with the added extensions, and the new profile became faulty.
I copied the prefs.fs file from the NEW profile to my default faulty profile, and the problem disappeared.
In the prefs.js file that you posted I see that hardware acceleration is disabled.
Does toggling hardware acceleration has any effect?