OK, a lot of users reported the script errors they are encountering on this forum using Firefox (here - [Only registered and activated users can see links])

Ive managed to single it down to one particular script I think. I only get the error when it has the following in the status bar at the bottom of Firefox -

Read Kona.Kontera.com

Hope this helps narrow down what is causing some of us Firefox users this problem!

install firefox adblock available as extension..and add this in tools>>>adblock>>>preferences "[Only registered and activated users can see links]"

kontera has some issues and problems with firefox!!

Thats solved it, thanks!