Symptoms
There was Parallels Server installed on the computer and removed with help of in-build uninstall wizard.After that, when one tries to install Parallels Workstation on the same computer, the following error message is displayed:
"Parallels Workstation can not be installed on this computer. Please, uninstall Parallels Server and try again".
Installation fails.
Resolution
This problem happens because of incomplete deletion of Parallels Server and several keys left in the Registry.To remove unnecessary keys, please, use Windows Installer Cleanup Utility as described in Microsoft Knowledgebase article:
support.microsoft.com/kb/290301