Just another datapoint (and I now have Shockwave Flash updated in case that was it — clearly it wasn't):

This is the first thread I go to in FT each day. Today, it is freezing when scrolling (and then unfreezes) but no error messages are appearing for the first time. Just the freezing. I have noticed the freezing occurring all the time in the United Mileage Plus forum since I reported this problem, but never (so far) in the Trip Reports forum or the Community Buzz forum. Don't know if that's a clue.

Update: United forum almost impossible to use today with much freezing and yes, the script error messages have started again.