Resolution
A. If you own a copy for Parallels Desktop 5.0 Full (not upgrade), please choose the "Activate Product..." option from the Help menu and insert the activation key in the activation form.B. If you purchased Parallels Desktop Switch to Mac edition please download and install Parallels Desktop 5.0 for Mac, then choose the "Activate Product" option from the "Help" menu and enter your Parallels Desktop Switch to Mac activation key.
C. If you have a key for Parallels Desktop 5.0 Upgrade, please choose the "Activate Product" option from the "Help" menu and:
1. Enter your Key for PD 5.0 Upgrade in the activation form and press 'OK'.
If the 5.0 installation does not automatically detect the previous version key,
2. Enter your Activation Key (Full key OR an Upgrade one) for previous version of Parallels Desktop (either 3.0 or 4.0) in a pop-up window and press 'OK'.
Be advised after 5.0 Upgrade key is entered, the previous version key you would need to enter should be a Full/Upgrade key for either version 4.0 or 3.0. In case you enter the one for 2.x version activation will not be completed.
Please be sure that you register Parallels Desktop for Mac activation key at your Parallels account.
D. If you have Parallels Desktop 2.x for Mac installed please check the following KB article for the instructions: http://kb.parallels.com/en/6815