File scans Right click on the Start menu icon and from the revealed list choose 'admin command prompt'. Type: sfc /scannow press enter and await results
In the same command prompt and after the above scan has finished type: dism /online /cleanup-image /restorehealth Press enter and await results (longer this time).
If the first scan found files it could not repair but the second scan is successful, run the first scan again using the same command prompt box and this time it should repair the files found.
As Kemical advises. I am thinking it may be something that has changed in the bios. I would suggest you open the bios and run through all the functions. It could be, but unlikely, the boot sequence.