This is the issue with open source that pisses me off. I was running 1.4.2 of jQuery and then upgraded to 1.4.3. Well it turns out versions 1.4.3 makes Firefox through these errors. The jQuery guys are blaming the FireFox guys. The FireFox Guys are blaming the jQuery guys.
If you are getting the error: “unknown pseudo-class or pseudo-element ‘sizzle’” then just revert back to jQuery 1.4.2!
Please note this has NOT been corrected in jQuery 1.4.4. The error in 1.4.4 is: