John,
Either it is malware or the OS is corrupt/damaged. There are a whole slew of things to do for this... the last ones being Restore, Refresh or Rebuild but, 1st...
When did this start?
What security are you using?
What did you use to check for viruses that said it was clean?
Is the machine brand new?
Please do the following:
(Oh, I just remembered your cmd won't work)
Run a full scan w/ Malwarebytes
Tell the machine to do a Disc Check - Rt Clk on C:/, Lt Clk on Properties > Tools tab & hit Check Now
Cheers,
Drew