Firefox issue

I'm having an issue with Firefox when using Facebook. Every so often I'll get a script error box pop up (see attachment). 📎Firefox_FB_error.jpg As you can see I can chose to either continue or stop the script. If I select continue then the pop up comes back shortly there after, and it will repeat this over and over as many times as I select continue. If I select stop it may take a few repeated tries to get it to stop. After I get the script to stop then FB and any other pages I'm trying to view in Firefox will be slow and laggy until I close Firefox and reopen it (closing and reopening just FB isn't enough to get rid of the slow laggy response). There are times when it gets so bad that Firefox crashes and I get the "submit crash report" and "reopen Firefox" box. Does anyone have any ideas how to fix this issue so it will not give me this script error and cause me to have to restart Firefox just to have normal web browsing.

Have you tried using IE to access Facebook for awhile, see if the same problem occurs. If not, try completely uninstalling Firefox then download hte latest version and install it.