Hi,
Thank you for posting your issue on Microsoft Community Forums.
Open a Command Window in Administrator privileges to do so follow the steps as mentioned below:
a. Click Start
b. Type cmd.exe
c. Under program right click on CMD and click on run as administrator (If you get prompt Allow the access)
d. Type sfc /scannow (Under command prompt and hit enter You’ll see the system scan will begin)
The scan may take some time and windows will repair/replace any corrupt or missing files. You might be asked to insert your windows 7 DVD if it’s needed.
Refer to the link for assistance:
How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7http://support.microsoft.com/kb/929833
After SFC scan, you can clear the files in temp folder.
a. Click start; in the start search type %temp% and press Enter.
b. Select all (Ctrl + A) and delete all.
c. Start disk cleanup.
Once you complete with sfc scan reboot the computer and try to run disk Clean up again.
Also refer:
Start Disk Clean up
http://windows.microsoft.com/en-US/windows7/Start-Disk-Cleanup
Delete files using Disk Cleanup
http://windows.microsoft.com/en-us/windows7/Delete-files-using-Disk-Cleanup
Note: Disk Cleanup removes temporary files, empties the Recycle Bin, and removes a variety of system files and other items that you no longer need
Hope this resolves the issue.