I don't know if this is related to the down time earlier in the day, but afterwards  I have been getting a lot of messages from Firefox about "unresponsive scripts".  I was not experiencing this problem at all this morning, or even prior to today.

FWIW, the error seems to occur primarily when I go to the url for a Vote Chess game in which I am participating;

http://www.chess.com/votechess/game.html?id=7329855

 It does not occur for other vote chess games where I am not a participant.

I have this problem in games with a lot of messages in the chat box.

I see the problem  only in one computer with firefox 2 + linux (but I use also another pc with firefox + linux and the problem is not present).

I think you can solve the problem following the instruction for example here

(I have not checked this yet... so I am not sure)

There is an option at the base of each page called Report Bugs

where you can report things like this.

I've had that error aswell, quite a few times. It usually appears on my machine if i have been using the computer for a long period without a reboot, or haven't refreshed my browser for a few hours after surfing umpteen pages. It also happens if i have a high cpu rate.