I switched to another library to see if it was having the same issue -- it was not. I've repaired permissions and repaired the database -- still having the same issue. Does this indicate a corrupted Library?
That does indeed look like something may be wrong with your library.
Should I try the (ominous sounding, according to the documentation) "Rebuild Database" option -- or should I try to create a new libary with the same images to see if that fixes things?
If you create a new library with the existing images, you will have to start over and redo all your edits.
Try first to rebuil the library. That will create new database files inside. But make sure that you have a backup of your library, before you try a rebuild, just in case.
Have you checked the "Export preset" that you are using, if anything can turn the images black: set the preset to "edit" and look at the options, i.e. color profile or watermark.
Thanks for the suggestions. As I've continued to troubleshoot, it now seems as if ALL my libraries are similarly affected (which perhaps means there's something wrong with Aperture). Also, I've never adjusted my export presets (or used watermarks), but to be safe I reset them to default (still having the same issue). Before I rebuild the library I'm going to try to delete the preference and reinstall the program -- hopefully that'll do it.
As I've continued to troubleshoot, it now seems as if ALL my libraries are similarly affected (which perhaps means there's something wrong with Aperture).
If all your libraries are affected, it still can mean, that some of your preferences are problematic, or startup items in your account are interfering.
Have you tried to work with Aperture from a different user account? Try from the guest account, if you see the same there.
If it works from a different account, remove preferences and presets as described here:
Hey Everyone, thanks for the help. I seem to have remedied the situation, although I can't for the life of me figure out what was causing it.
For the record, I never made any custom export presets (and would get the same results from different default presets). After trying a number of different things, I ended up deleting the preferences file and rebooting the computer -- which seems to have returned things back to normal.
It's a little worrysome since I don't know what caused it (or if it'll start doing it again), but I appreciate all the tips!