when you click on a block and move the mouse if the arrow happens to be over one of the other control buttons buttons when you release the left click this is what causes the game to freeze and display the screen that you see.
If you click retry while holding a group, I know it does that. I'll test to see if it's everybody's problem. Similar thing hapened to me in JG2, when it reached a certain time on this level I made, the level stopped.
edit: Doesn't happen for me. That's too bad. :( Hope it evetually works for you.
But at least I solved it.