iCal "hanging"

I have noticed that from time to time iCal will "Hang" you do not get the spinning ball, there are few visible signs that it is in the "hung" state. The menu is all "greyed" out and if you try to select a day or event you can't.

The only way to get out of this situation is to Force Quit iCal and start over.

Anyone seen anything similar ? is there a fix?

John