I too seem to be experiencing the same thing but I have found it to happen whenever a dialog box opens, such as when conforming, saving, deleting, exporting and the like. I still have not figured out why because it does not happen all the time, just whenever it gets a wild hair  ;o)
I think the worse part in my case is that it can happen right in the middle of a session.....one second it's working fine and the next time you open a dialog box......BAM!!!  Not Responding
Very frustrating
I hope this gets sorted soon..............