I may be wrong here but it sounds like one of two things to me. One your hard drive is failing or more likely you picked up a bad virus.
Run CHKDSK trough Command Prompt
1. Open an elevated Command Prompt (Press the Windows + X button at the same time, then choose Command Prompt (Admin))
2. Type the following command, and replace the X with the drive letter you wish to scan: “CHKDSK X:”, we suggest you use “CHKDSK X: /F”, only then it can correct errors.
3. Hit the enter key, Command Prompt will now start CHKDSK.
To check for viruses do the Security Tango:
http://securitytango.com/Nick is from Rochester NY and on his weekly radio help show says this is still the best method to rid yourself of those bad things.
Good luck and I hope this helps.