I have a file which, upon opening in CS6, changes part of the text to symbols and keeps the rest normal. The fonts that change are Helvetica (TT). I even changed the font to Helvetica regular and it remained as symbols. What's weird is if I select everything on the page and paste it to a new document, it goes back to normal. But if I save, close, then reopen it changes to symbols again. I had someone with CS5 open an IDML version and it looked fine on his computer, but when he tried to package the fonts it kept locking up. Any ideas?!? It is a huge pain to try to get a 4 page newsletter out if I have to copy and paste the whole thing each time I open it!
What do you know about the file history?
You can learn quite a lot, usually, byt holding the Ctrl key on Windows or the Cmd key on Mac and choosing About InDesign fro either Help (Win) or InDesign(Mac) menu.