I've just updated Firefox to 23 and the Norton extensions are working fine, no incompatibility.
Make sure you update Norton via Live Updating, restarting if required, BEFORE you update Firefox.
So you got the Norton Patch before the FF23 release .....
Well done Norton!
And some chose to attack the Norton / Symantec team for not catching a late minute code change in FF22...
They nailed this one!
You guys rock!
Joining the happy people...
From me too, well done Norton!
Laura 