IPhoto suddenly wants to export only unedited photos now. Why do no crops or light/colour adjustments get saved?

Question

INTRO: I have used iPhoto for many years (since iPhoto 5 I believe). As a non-professional photographer, I have been very happy with the application, as it has let me do most operations I need: Photo organising, adjustments of light, levels, contrast, colour balance, straightening and crop. (I haven't even had the need for Photoshop Elements for several years.)
I usually make some adjustments to each and every shot – some big and some small – before exporting as a high quality JPEG for uploading to Flickr or other places I use them.
PROBLEM: I have recently upgraded to a new Mac and iPhoto '11, and have been using this version happily for about a month now. Earlier this week, straight out of the blue, iPhoto has decided "all by itself" to stop saving edited/adjusted/cropped JPEG exports of my Nikon RAW photos, and instead only saves the unedited version as a JPEG. None of my crops or light/colour adjustments get saved anymore! (I first noticed when a closely cropped shot came out uncropped, and a shot I'd converted to black/white came out in full colour.)
(Strangely enough, it seems iPhoto treats "original JPEGs" differently, as shots from my non-RAW cameras get exported with my edits preserved.)
Has anybody else experienced the above described problem with exporting photos? Is it a bug, or is it some setting somewhere that I am not aware of? If I can't resolve this issue, I will have to stop using iPhoto and find a new "photo lab" and establish a new workflow. I hope I don't have to.
Best regards,
Jørgen in Oslo, Norway

Answer 1

Hi again, Terence, and again thanks for your advice.
I tried the Rebuild Library operation during the weekend, but having some 160 GB (1400+ events and 20000+ photos from 2007–2011) in my main (corrupted) iPhoto library, the operation seemed like it would be taking the whole of Saturday and maybe Sunday as well. I started the rebuild in the morning, iPhoto Library Manager chewed its way slowly through my photos, but iPhoto kept crashing every once in a while (especially often if other applications were running at the same time). When it had been working for about six hours, the import part was finally finished, but the metadata rebuilding process looked like it would be taking hours still, and I really needed to get to work on some other things on the same machine. So unfortunately, I had to abort.
Thus, on Sunday morning, I changed strategies: I decided to use iPhoto Library Manager to break off a smaller subset of my gargantuan problem library to a new library. I had already made a full manual backup of the corrupted Library to a USB external hard drive beforehand (and I also have continuous Time Machine backups), so I am pretty lax with "destructive" stuff right now, as long as they can fix my problem. This is how I'm working now:
I created a completely fresh and empty iPhoto library, and used iPhoto Library Manager to move a handful of recent iPhoto events from the corrupted library. I have now tried some edits and exports, and the new library is behaving healthy at the moment. I'm keeping my fingers crossed – if things work as good as they seem in the days to come, I will split up my entire, corrupted 2007–2011 library into separate sets. (Maybe one or two for each year.)
And in the future, I have decided to make a new iPhoto library every 1st January and 1st July.