Having trouble saving Word documents (2007)

For awhile, all is well, then suddenly I get "check temp files" type message and multiple questions about the normal file.

I've gone into the HKEY-USER-etc to temp files cache and reentered the right phrase. But still some documents tell me they're open when they're not.....I got a message finally that told me perhaps a program was blocking the files, some of which are pretty old. Any thoughts?