Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

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

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

In Firefox 4 you can use one of these to start in Safe mode:

• Help > Restart with Add-ons Disabled
• Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)

Hi cor-el, thanks for the reply but going into safe mode did not solve the problem. Still unable to view flash videos other than on youtube :(

going by all the complains on this forum and around the web, firefox has really screwed up a great product big time with FF4.

Try "Reset all user preferences to Firefox defaults" on the Safe mode start window.

Create a new profile as a test to check if your current profile is causing the problems.

See:

• Basic Troubleshooting: Make a new profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Again, really appreciate your help cor-el. However, have done the new steps suggested and the problem still persist. :(