Odd Windows 7 Registry Error

This morning we areΒ at Leamington Spa and have a Dell Desktop PC with a registry error on boot up, This appears to have been caused by a McAfee internet security upgrade going wrong, on this one we had to restore the system to an earlier date, run the windows updatesΒ  untill all up to date then reinstall the Mc Afee upgrade as downloaded from the internet .