This happens for me pretty often. Useally they come up if you wait, but sometimes you have to refresh the page.
No Pieces

Well after much ado. I decided to clear my cache and clean all my personal data and the pieces were back next time I reloaded the page.
Guess it was just me.

I think your solution is to click the mouse outside the board.
Tried that, even tried the old tried-and-true (windows trick) of shutting down and restarting, but that still didn't work. I logged out and back in. Refreshed numerous times. Exited Firefox etc. Nothing was working.
Clearing the cache, seemed to do it.
Today when I went into my waiting games. No pieces displayed on the board.
I use Ubuntu 8.04 (and love it), Firefox 3.0.7.
Anyways I can't think of anything I've done to change my system and no other web pages are obviously acting up.
Am I alone or has anyone else had this issue?