The I would try uninstalling manually. I would start by
Deleting Delete C:\Programs Files\Cyberlink\PowerDirector
Then go into registry as noted below
Start --> Run --> type "regedit" --> click "HKEY_LOCAL_MACHINE" --> click "Software" --> locate "Cyberlink" ----> click the "+" (if you have more than one CyberLink product) -->Delete the "PowerDirector" folder
Start --> Run --> type "regedit"--> click "Hkey_Current_user" --> click
"Software" --> locate "Cyberlink" ----> click the "+" (if you have more than one CyberLink product) -->Delete "PowerDirector" folder.
Then I would search anything that said Cyberlink or Power Director (if you have more than one Cyberlink program on there, be careful what you delete) get rid of anything that pertains. I think I heard that PD7 won't open previously saved working files, so you might want to make sure you are done with your projects OR have noted the information about them so that you can copy them again in PD7.
I would then reboot and try to install PD7 after that.
Hope that helps.