Try Firefox Safe Mode to see if the problem still exist. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

You can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.

TyDraniu 说

Try Firefox Safe Mode to see if the problem still exist. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). You can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.

same. i cannot open my league of legends client too, not sure if related

Any luck with booting the computer in Windows Safe Mode with network support (press F8 on the boot screen or hold down the Shift key)?

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

This could be a font issue since starting Firefox in Safe Mode where hardware acceleration is disabled didn't had effect.

• Firefox 53.0.2 Crash Report [@ @0x0 | dwrite.dll@0xb039a ]
• 17 xul.dll gfxDWriteFontList::CreateBundledFontsCollection(IDWriteFactory*) =>
  aFactory->CreateCustomFontCollection(loader, &key, sizeof(key), getter_AddRefs(collection));

The crash report flagged several Windows programs.

Perform a System File Check to fix corrupted system files

Win 7, 8, 10, Vista: https://support.microsoft.com/en-us/kb/929833 Win XP: https://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/system_file_checker.mspx?mfr=true

Wiki - Windows 10 System File Check http://answers.microsoft.com/en-us/windows/wiki/windows_10-update/system-file-check-sfc-scan-and-repair-system-files/bc609315-da1f-4775-812c-695b60477a93