When this happens, it means that there is a module which is failing to start. It could be a corrupted file, a registry entry, etc. I would like to recommend a reinstall operation, but first make sure to remove the software from your computer using Revo Uninstaller. It will force it to uninstall by wiping out all traces of its presence from the system.
Once Revo finishes, reboot the computer then re-install McAfee and it should work.