Errors or malware ?
Windows (I am assuming its windows) has a utility to check and fix problems with the file system CHDSK click here
and one to check and fix problems with the system files SFC click here
If you want to scan for malware take a look at these
Malwarebytes Antimalware Free click here
SuperAntiSpyware click here
Spybot Search and Destroy click here
Remember to get latest updates before using