I figured out this trick a couple of years ago with the InDesign CS2 beta. Since then, because InDesign converted document corruption is so prevalent and insidious, I’ve been preaching the below technique to everyone I know. Thus, you may have already heard about it. Just in case…
When opening QuarkXPress, PageMaker, or even earlier version InDesign documents into InDesign CS2, there exists a risk of file corruption. If it occurs, you probably won’t notice it until days, week, or months down the line. That’s when, all of the sudden, you’ll be unable to open your document, or unable to print it, or, after working in it for a few hours, find that the Save and Save As menu options have grayed out.
Hedge your bets against future corruption by eliminating it from the start. Immediately after converting a document from an earlier version of InDesign or from QuarkXPress or PageMaker, save it as a normal .INDD file. And then go to File > Export, and, at the bottom, choose InDesign Interchange format, which forces a rewrite of every line of code in the InDesign document. Now, open the .INX file you just created, and save it back to a normal InDesign document with File > Save As. This new document will be clear of any corruption that crept in during conversion, and you can safely delete the .INX and other versions.