If you have/had any other antivirus installed use their removal tool, if there is one, to make sure it's gone. Also if you happen to have Spybot Search and Destroy and/or Malwarebytes anti-malware applications installed, uninstall them temporarily.
Then run the MCPR removal tool to get rid of your partial installation, available via Useful Links at the top of this page & reboot and then try again.
How old is that CD? If you had McAfee installed before you will have an online account which would be the preferred download point.
This could also happen with certain malware, have you had any strange things happening lately?
By the way once this is sorted out, make sure you update Windows 7 to SP1, there's help with that here: https://community.mcafee.com/docs/DOC-2205