The prompt will change to Diskpart.
At the Diskpart prompt type the following and press Enter after each line:
Select Disk 0 (That is; Select Disk zero)
You will be presented with a list of volumes within the disk. Note the letter assigned to the volume labeled Windows7_OS.
Type Exit and press Enter to leave Diskpart.
At the X:\windows\system32> prompt type the following and press Enter:
CHKDSK A: /R
Where A is the letter assigned to the volume labeled Windows7_OS in Diskpart.
Please let me know if there are bad sectors or clusters on this volume.