It probably is corrupted, This can happen with infections, frequent use of System Restore or using registry cleaners and tune-up utilities. What is your operating system and service pack please?
Right-click Computer (My Computer if XP) and select Properties, that will give you that information.
I suggest you uninstall via Control Panel in the normal way.
Then run the MCPR cleanup tool located in this FAQ
Reboot and reinstall the product from your online account.