It may sound stupid, 'cause it's happened to me, as well, but try to just go to the Emulation tab and hit Run if/when it freezes. You should be good after that.
Then, you just continue doing that if it freezes. Finish your mission, save, and things should go back to normal.
Then, you just continue doing that if it freezes. Finish your mission, save, and things should go back to normal.

