Originally Posted by Rob-F
Must be a glitch in the new update
I've seen similar symptoms before with Aperture 2. In OSX, the raw conversion is done by the operating system, not the application software. You can test to see if the problem lies with the raw conversion or with the application by trying to open your raw files via the Preview application. (ie, just double-click on them in the Finder and they should open in Preview. Alternatively, run Preview and then do an "Open" on one of your raw files).
I've seen the symptoms you describe with Aperture 2 but with a different digital camera, it is a known problem with Aperture 2. I didn't have the problem very often, and it was usually "fixed" by simply quitting and restarting Aperture.
For what it's worth, I have yet to see this problem with Aperture 3.