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FireFox window(not the screen) has turned red, since then it has been running very slow.
Just bought a new computer (non Mac), it has windows 8 with an intel i5, Fire fox browser is outlined in red, it was white for about 1 day then turned red. The since it has been outlined in red it either loads web pages very slow or doesn't load them at all. it is running so slow I had to do this from my old computer.
ప్రత్యుత్తరాలన్నీ (1)
This can be an indication that some (security) software is running Firefox in a sandbox environment.
Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps to identify the cause.