Cannot open file-box says mscx: [note : !]

I have opened files from this particular location every time I use MS. This time, after 4 hours of work on the file, I got the familiar," MS has encountered a problem and needs to close program" . I closed it and opened it back up; It asked if I wanted to restore previous session, as usual; I clicked "yes". It was then that I got a dropdown box telling me that my location was "bad format" and indicated that it was looking for my piece under .mscx: [note the colon at the end!] That is NOT how it is saved, but no matter what I try, I cannot make it look for my file without the colon. Please, has anyone a suggestion?
Thanks!
Scott