We would need more details to pinpoint any issues.
What operating system is this and is it up to date?
Have you tried restarting the machine (not sleeping and waking up, powering completely off and restarting).
If you have Windows 10 this can be prevented by what's called Fast Startup (not really any faster).
Turn it off, tutorial here: Windows 10 Forums
Also try the McAfee Virtual Technician which can often diagnose issues and fix them for you. http://mvt.mcafee.com/
On that same page is a "Contact Us" button which can be used to obtain free Technical Support if you wish.
Alternate download link: McAfee Virtual Technician
Moved from Community Support to LiveSafe