Finally I get it! To preserve the MS Office Recent Document lists that pop up within MS Office apps, Exclude the folder below from CCleaner. This is where MS Office stores a link for each Recent Document (MRU data) seen within the MS Office Apps. The path below works for WIn7 - Office 2010 and for Win8 Office 2013.
C:\Users\YOURACCOUNT\AppData\Roaming\Microsoft\Office\Recent\
Of course, substitute your account name for the YOURACCOUNT information.
In CCleaner Select: Options, Exclude, Add, Folder, and browse to the one listed above.
