v0.14 working but unable to quit or exit the program

[BermudaJohn]

Some additional testing results:
- Running the same test on my Windows 7 x64 partition yields the same unresponsive behavior with the .exe version of the program
- If I remove one of the cards and just test with the 6870, everything works normally.

Is this a common issue with multiple GPUs or dissimilar GPUs?