Since I install the latest build (5608) I get an error message at start up that says something to the effect that Parallels can't find a driver and to reinstall and start Parallels from the Applications folder. I had been starting from an Alias in a folder on my dock so I didn't reinstall but started Parallels from the Apps folder and it worked just fine. Thinking that the recent build changed something I deleted the Alias from my dock folder and copied Parallels there instead by dragging the icon from the Apps folder. I still get the same error message and have to start from the Apps folder.