Since yesterday, I've had repeated hangs (6+) on puzzle 905 when trying to run Acid Tweeker v1.78:

   http://fold.it/portal/recipe/43760

I've shared one of the problem solutions to scientists, though this occurs on a different 905 solution as well:

   gw9717.496 solo.

The problem should be reproducible.

build: 20140529-5bf0c97d7b-win_x86-devprev

Note: I have applied the temporary fix to the graph undo variable to no avail. It would be nice if a permanent fixed could be included in the next update.