Aperture constantly hangs during long sessions
I am using the latest version of Aperture. I tend to do editing work for stretches of about 4-5 hours at a time in full-screen mode. At least once a day, Aperture hangs in the middle of a session. I suspect it's when I'm brushing in a change, but I've also seen it even during cropping (often I'm going back and forth making minor adjustments). Usually I wait a few minutes to make sure it isn't coming back, then I force-quit Aperture and then re-launch it immediately and it works again for a while, but eventually it comes up with a dialog saying the database is inconsistent. I have rebuilt the database from scratch several times, but Aperture still hangs. I just upgraded to the new version a week or two ago and it's still unstable for me.
Has anyone else been having this problem? Is there something I'm doing wrong? I'm using a 27" mid-2011 iMac with 24 GB of RAM running the latest version of OS X and I'm not having any problems with other applications.
Thanks for any help or suggestions.
iMac, OS X Mountain Lion (10.8.4), Aperture 3.4.5