I use ^ + number keys to switch between my OS X Spaces. When I do this to switch away from my Windows 7 VM running full screen in Space #2, the number for the number key I pressed shows up in the Windows application with the input focus. For example, if a command prompt window is the active Windows application, pressing ^ + 1 to switch from space #2 where the VM is running to space #1 will cause 1 to show up in the command prompt window. This behavior is new in Parallels Desktop 6. Support ticket #1001064 has been submitted for this issue.