That command, REN C:\Program c:\Program1 contains spaces, ie;
REN{space}C:\Program{space}c:\Program1
Did your command have the same spaces?
This may be a folder or a file. To check, use Windows Explorer, or My Computer, to search for all files and folders on the root directory, (the C: directory).
In My Computer click the Folder icon in the menu bar. This will change the display to a two-window paned display with Desktop showing in the left hand pane, and underneath that the words "My Computer". if this has a + sign by it, click that to expand My Computer. Highlight the "Local Disk (C
" and click the + sign besides that.
Make sure that "Show hidden files and folders" has been set by going to Tools > Folder options, then the View tab, and change the option under "Hidden file and folders". For good measure scroll down the list and unselect "Hide extensions for known file types", and also unselect "Hide protected operating system files (Recomended". These will display all hidden files and folders on the C drive.
Look down the list in the right hand pane for anything that says Program. If it is a file, tell us what file extension it is. If it is a folder, look inside the folder and tell us what is inside.
Whenever you have done this, return the hidden files and folder options above to their original values.
Mark