I used to use Disk Cleanup YEARS ago and it works no problem on a HDD Windows 7.
Now I just ran Disk Cleanup (with default settings - which is to clear temp folder, clear recovery/rescue files, update files, etc. etc).... on my SSD C:\Windows 7 - I do still have the old Windows 7 on the D:\ HDD (which was cloned to C:\ using the Samsung 840EVO SSD clone tool CD.
After reboot - Windows fails to start. It forever keeps on System Repair - reboot - System Repair - reboot - forever. It says lots of files are corrupted.
I tried to do a recovery - but it says my recovery files have been deleted. I tried installing Windows 7 ontop of my existing Windows installation (Upgrade option) but it won't let me - saying Windows was previously installed via Windows itself...
PSS: actually, I think I deleted the Windows folder from the old HDD already - so no way booting up there.
Microsoft Disk Cleanup options:
Downloaded Program Files
Temporary Internet Files
Game Statistics Files
Service Pack Backup Files
System error memory dump files
Per user queued Windows Error Reporting
System queued Windows Error Reporting