On several occasions I tried maintaining an Aperture Library with my 30,000+ photo library (mostly RAW) and found that it was constantly unreliable and crashing. After using Aperture for about 3 years I finally pulled the plug and went with Lightroom 4. Each has it's own advantages & disadvantages but I'm not arguing this point. The issue with the crashing could be with SuperDuper which I was using to clone my external drive which held my aperture library and photos. I've really never had any issues with SuperDuper and thought very highly of it but this week I noticed when it clones the drives it unchecks the "Ignore ownership on this volume" on both the original and clone. I guess this wouldn't affect the normal user who has one user and imports from one user but I had 2 users on on 1 mac and each of us would import into the drive independently on each others account. I researched it online and users have reported the SuperDuper & "Ignore Ownership on this volume" for several years. I'm going to guess that Aperture would be finicky about the sharing and permissions and that could be the cause of the crashing. Knowing this now I'm going to try once more and see if the problem goes away. Wonder if anyone else uses SuperDuper and notices that it unchecks this box from external drives.