The Firefox Firefox/8.0.1 version that you currently run is no longer supported with security updates.
It is important to update Firefox and add-ons to the latest versions to get the latest bug fixes and security updates.
Clear the cache and the cookies from sites that cause problems.
Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).
Do not click the Reset button on the Safe mode start window or otherwise make changes.