Resolution
Try reinstalling Parallels Desktop. This should fix it.
Go to Finder> Applications> Right click Parallels Desktop> Move to trash. Empty trash.
Download a new installer. Try downloading the trial version here:
http://www.parallels.com/products/desktop/
Even using the trial version will install it with the original full version product key automatically.
P.S.
I had an experience with a customer where he keeps the Mac turned on all the time. Only puts it to sleep when he leave. I first removed Parallels Desktop, ran Disk Utility (Finder> Applications> Utilities> Disk Utility) and Repair Disk Permissions for Macintosh HD then I had him reboot the Mac and started fresh. Then we downloaded and installed Parallels Desktop. It worked perfectly fine.
Last edited: Mar 28, 2012