I have read the other threads and tried what they suggested and am still unable to solve this.
I am using OSX 10.7.5
I have tried uninstalling and reinstalling firefox. This did not work.
Create a new profile as a test to check if your current profile is causing the problems.
See "Creating a profile":
If the new profile works then you can transfer some files from your old profile (if there is one) to that new profile, but be careful not to copy corrupted files.