One possibility is an incompatibility with your graphics card/chipset driver software. The standard workaround for this is to disable Firefox's use of hardware acceleration, or to update the drivers to a compatible version if available.

To test whether disabling hardware acceleration would work, you can simply run Firefox briefly in its Safe Mode. That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any improvement? To switch the setting so that hardware acceleration will be disabled when you close Firefox and start it up again in normal mode, you can use the Options dialog:

"3-bar" menu button (or Tools menu) > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

If you think this started in Firefox 33 rather than Firefox 32, it could be related to "Off Main Thread Compositing" (OMTC). There is a preference to disable this feature if you prefer to try that. I'm not sure whether this will enable acceleration to work in other places or not.

layers.offmainthreadcomposition.enabled (default is true, try false)

i have disabled all the add ons and uncheck the excelerator as suggested, the end result is the same, no change, you mentioned in your close to change the omtc from true to false, how is that accomplished?

To change the OMTC setting:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste layers and pause while the list is filtered

(3) Double-click the layers.offmainthreadcomposition.enabled preference to switch it from true to false.

I think you might need to exit Firefox and start it up again before that takes effect.

Did you close and restart Firefox after toggling the hardware acceleration setting?

You can also try a different Windows theme.