Your file may be toast, but here are some things you can try:
See if a trip through IDML is possible: Remove minor corruption by exporting
Move the pages into a new file using the Move Page command in the Pages panel flyout menu.
Copy/paste the content into a new file.
Export the text to InDesign Tagged Text and place that into a new file.
Thanks P Spier, we think this may be to do with a recent installation of Anti-Virus, my user has stated the following:
"Yesterday I copies all my pages over to a brand new file….deleted the corrupt file….and now this new file is having the same problem.
I find I can make a copy of the file on my desktop but I cannot save the same ( edited version) file…it will give me the error and then it crashes."
Which A/V do you use? Have you tried disabling it, or running System Restore to go back to an earlier version of it?