hello aujpoj, other users with this problem all had an embedded intel hd graphics card with an old driver present. in case this also applies to you, here would be a link to update the driver, which in turn should also address the black firefox problem.

• Intel HD 2000/3000: https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=23764 (for win7 64bit)
• Intel HD 4000: https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=24329 (for win7 64bit)

in case this doesn't solve the issue or does not apply to your system, start firefox into safemode by pressing the shift key while the application is launching & disable hardware acceleration in the firefox menu ≡ > options > advanced > general (that setting will take a restart of the browser to take effect).

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Sorry. How do I know if the Intel HD 2000/3000/4000 applies to me? I don't know what these are. Thank you!

Used the shift key while opening Firefox, disabled hardware acceleration, seems like I'm back in action. Thank you, Philipp!

hello, this is the kind of graphics chip that is built into your computer. here's a how to by intel to find out which one you are using: http://www.intel.com/support/graphics/sb/cs-009482.htm

edit: now that it is working again, could you go to the firefox menu ≡ > help ? > troubleshooting information, copy the contents of that page and paste them here into a reply on the forum? then i can give you more specified advice regarding your graphics driver.