If you've been running any registry cleaners stop as those destroy your system and cause similar problems to this.
Make sure you've removed any other antivirus and used their removal tool if applicable.
Open IE10 (whether or not you use it) and go to Tools/Internet Options/Advanced and click Reset and OK any prompts,, Apply and OK
Close and reopen IE10 and go to Tools/Add-ons and re-enable any you need.
Uninstall any McAfee entries in Control Panel > Programs
Run the MCPR cleanup tool and reboot.
Run the mcpreinstall tool
Try your installation again.