Unless you can spot a difference between files on your own, you may need to report this as a possible but in Report an Issue yourself to see what the techs say.
Before doing that, I'd first recover the file in question and test the recovered copy just to rule out possible issues with the file.
Thanks for the response. I performed a recovery to the file but to no avail. Same behavior still occurs. Still hoping there is a quick answer to this issue as I need this to work this week. This never would have been a problem but our University just switched us to Outlook. I guess I could configure my computer to use a non University email client to get through this critical notification, but it's kind of lame if this is my only recourse. I'm not a regular on these forums, but maybe I should be. If I need to submit this as a bug I guess I should.