The location might be an issue, or the file got mistakenly quarantined by OS X, which has been happening on Mountain Lion (even to TextEdit, I believe...). I'm unable to go web-browsing for the quarantine bug issue, but the first thing I'd suggest would be to duplicate your file and start using the new duplicated one.
(I don't have all-day/every-dy Internet or faster than slow DSL at the moment and weekends are busy/offline right now, hence a not-immediate response to the original post; I get all posts via email, no worries there).