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

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be careful not to copy corrupted files.

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

Thank you for helping. But my current profile is not causing the problems. I just got this profile a couple of days ago. Firefox has been like this for the last couple of weeks.

FF doesn't work for me either - constant freezes ever since version 3.5 _ I now have version 25. Why should all these adjustments and workarounds be necessary ? Other browsers ( and there are plenty ) work straight away.

My opinion is that Firefox has a fatal flaw.

Every time I've encountered the problem, I've trashed FF and its associated files, waiting for a new version, which I've installed, hoping for an improvement. Every time, the problem has returned.