[SOLVED] Categories disappear from bar when upgrading to WP 2.8.3
 

I have already solved this, so this is just to let others know. Upon upgrading to 2.8.3 suddenly all my categories disappeared from the category bar, which just displayed 'no categories'.

The culprit is the My Category Order plugin. Upon de-activating, everything was back to normal, and again, after re-activating the de-activated plugin. But the whole thing had me panicking for a while until I remembered the same thing happened last time, going from 2.8.1 to 2.8.2.