McAfee Is Not Installingby Seth Amery
If you want to install the McAfee anti-virus program, you will need to make sure your computer doesn't have any conflicting software on it, such as other currently installed anti-virus programs or traces of previous versions in the registry. Otherwise, your program will not finish installing.
Verify that you do not have any other anti-virus programs installed on your computer. Access the list of currently installed programs by clicking "Start," then "Control Panel." Click "Uninstall a program" in the Control Panel. Search the list for any anti-virus programs, including any by McAfee.
Click the anti-virus program, if you find any, and then click "Uninstall" or "Remove" in the top of the window. Click to "Remove Completely" if prompted and continue clicking "Next" until the program uninstalls.
Erase any traces of previous McAfee software if you used to have it installed. Press the Windows logo and "R" keys simultaneously. Type "regedit" into the field and click "OK" to start the registry editor. Click anything with "McAfee" in it and press the "Del" key to remove it. Close the registry.