I moved this to LiveSafe as a better spot for it.
Try running the Virtual Technician to see if it finds a problem and corrects it. See the link and how to use it HERE.
If that doesn't help I suggest a complete uninstallation via Control Panel > Programs and Features
Run the MCPR cleanup tool and reboot
Then download & reinstall LiveSafe from your online account.
If all the above fail, then I suggest Technical Support which is free by phone here: Contact Support
If at first they don't succeed, ask for an escalation.
Broken link to French version of that FAQ above amended. BTW MVT applies to any Windows operating system from XP upwards.
I would follow Peter's advice and contact support giving them that MVT ID number though first try a clean reinstall ie uninstall as per below and reinstall from your account.
Thank you for your advice. I followed the doc for a clean reinstall. However neither the message Cleanup Successful, nor Cleanup Unsuccessful showed up after launching MCPR.exe and rebooting the laptop.
Anyway I still managed to reinstall McAfee, and I am now waiting to see if the same problem appears again.
Has the issue returned if not I shall close this thread.