PC hangs when 'stop debugging' nbody cuda sample in Visual Studio

Hi, I have VS2012 with Cuda 5.5 installed on windows7. When I compile and run the nbody sample it executes ok. however when I press the red ‘stop debugging’ button in Visual Studio, my PC hangs. I can move the mouse however I cannot interact with any of the windows. I need to hard reboot.

Can anyone else reproduce this problem?

Any help most welcomed. Thanks