**System Information**
Operating system and graphics card
win 7 64 gtx 580
**Blender Version**
Broken: (example: 2.69.7 4b206af, see splash screen) 2.74 rc4 3593082
Worked: (optional)
**Short description of error**
Preview render issue
**Exact steps for others to reproduce the error**
Based on a (as simple as possible) attached .blend file with minimum amount of steps
When fast navigate is active, preview render with shift+Z will crash when moving the mouse during render, as if retyping shitf+Z to stop render.