"This copy of iTunes is corrupted or is not installed correctly. Please reinstall iTunes"
Let's try a repair install of iTunes first.
Restart the PC. If you're using Vista or 7, now head into your Uninstall a program control panel, select "iTunes" and then click "Repair". If you're using XP, head into your Add or Remove Programs control panel, select "iTunes", click "Change" and then click "Repair".
Can you launch your iTunes now?