to get permission to do CHKDSK/f. you could try enabling the 'super admin account'
- Click Start.
- In the Search field, type CMD.
- On the list of available programs, right click the Command Prompt icon and click Run as Administrator.
- In the black window, type: net user administrator /active:yes
- Press Enter.
- The system should return you with the following message: The command completed successfully.
- Now, exit the Command Prompt and click the Start icon.
- Log off from the current account and in the Account window you should now see the Administrator account.
- If you want to turn off the Admin account, type: net users administrator /active:no
( copied from How to Turn On Super Administrator Account in Windows 7 | Web Talk