This sounds like system corruption or Malware...
Please download and install
Malwarebytes Anti-malware (free version) from http://www.malwarebytes.org/products/malwarebytes_free/ - UNtick 'Enable free trial of MBAM Premium' at the end of
the installation - and update it, then run a full scan
in your main account, and Quick scans in any other user accounts.
Quarantine everything it finds
THEN...
Please run a full CHKDSK and SFC scan....
Click on
Start > All Programs > Accessories
Right-click on the
Command Prompt entry
Select
Run as Administrator and accept the UAC prompt - the Elevated Command Prompt window should pop up.
At the Command prompt, type
CHKDSK C: /R
and hit the
Enter key.
You will be told that the drive is locked, and the CHKDSK will run at the next boot - hit the Y key, and then reboot.
The CHKDSK will take a few hours depending on the size
of the drive, so be patient!
After the CHKDSK has run, Windows should boot normally
(possibly after a second auto-reboot) - then run the SFC.
SFC -System File Checker - Instructions
Click on
Start > All Programs > Accessories
Right-click on the
Command Prompt entry
Select
Run as Administrator and accept the UAC prompt - the Elevated Command Prompt window should pop up.
At the Command prompt, type
SFC /SCANNOW
and hit the Enter key
Wait for the scan to finish - make a note of any error messages - and then reboot.
Upload the CBS.log file (compressed, please!) to your OneDrive or DropBox Public folder, and post a link - also post an MGADiag report.
