Hello. I have installed Windows 7 using parallels so that I can use coherence and run (the windows version of) office 2010. The problem? Simple really, the coherence mode is greyed out... I start windows 7, click View in the menu, and enter coherence is greyed out. I'm using a 24" iMac, no second screen.
Try to reinstall Parallels Tools (go to the Parallels Desktop Virtual Machine menu -> choose Install Parallels Tools).