I have yet to crash it, which I think is pretty impressive, but I did find that if I scan a huge (the size of my whole scanner glass) color image at 48 bits per pixel, 1200 dpi, Aperture will throw in the towel. It completes the import, but shows "Unsupported Image Format" in the viewer.
This makes a certain amount of sense, given that the image file is 489 megabytes.
Fortunately, Photoshop Elements -- yes, the one that came free with my scanner -- will open up this image and save it to a lower-resolution version.
This machine has 2.5 gigabytes of memory -- and that's all it will hold. I wonder if Aperture would handle it if it had more memory? There's always the possibility of getting an even beefier machine in the future.