NaN indicates "Not a Number," the result of an invalid floating point arithmetic operation, like division by zero. That's not necessarily helpful.
Have you tried exporting to IDML and opening that, to see if it clears the problem?
This does sound like a new problem.
I stupidly started trying to figure out what was going on rather than immediately doing a save as and within about 3 minutes InDesign crashed. When I relaunched and reopened my document, not only were my graphic frames still messed up but all of the content on about 5 other pages were completely gone, frames and all. This is the weirdest thing that I've ever seen in InDesign. I understand the concept of NaN. I just mentioned it because it seemed like part of the problem. Thanks for your reply. What makes this even more interesting is that this isn't the first time that I've seen this. About 6 months ago, I saw the same issue happen to another user on another machine. At that time we couldn't really track down any details because the document was last accessed at the end of the day on a Friday and we didn't figure it out until Monday morning. The only thing that the two workstations have in common is that the documents and resources were stored on the same server. Could it be an issue with using InDesign files stored remotely vs locally?
Indeed it could be.