(This is a problem with Windows 7 machines with User Access Control)
The short of it.... You need to install with elevated priviledges during the install. If you have already installed MapPoint and are perplexed by this really annoying message the try opening the Command Prompt by opening the Start Menu and
Right-Click on Command Promptt to use the RunAs Administrator option. Once open navigate to your CDROM drive.
C:\> D: <-if you have a D: drive for your CD
D:\> MapPoint\MSMap\data.msi <- run the installer again
During the install use the REINSTALL option.
Once the application has completed the installation you should be able to run it from the Start Menu without issues. I hope this helps. as it helped me.