Hi , might be time to revise your security program and application licenses relative to computer usage - comodo offers a full security suite freeware for computer business use if desired and applicable to you.

As for your issue , my guess is malware , a virus 

However if not done so, backup all valued personal files to external storage 

Try running full system file scans of currently installed security application programs within Windows "safe mode" , which is selected via the start menu accessed by repeated clicking of the F8 key during computer start  (power up / booting)