Have you got another Antivirus installed or had 1 installed if so you need to run its own removal tool and then maybe reinstall McAfee.
that said try running the MVT self help tool it might find a corrupted file
Those are my initial thoughts you could reinstall McAfee following the steps mentioned here
Other thoughts are your PC specs are low wrt cpu and memory try running the scan if it is a scheduled scan using minimal resources it not set so already.
If all above no good you will need to contact support at least the reinstall should prevent their suggesting that. Oh also note the MVT session number that is shown on the right side of the MVT screen.