same thing happens here, whenever i customize the collections it crashes after +-5 seconds.
i'm running mac os 10.6.7 and calibre 0.8.8. I had 0.8.9, but since i crashed i went back to 0.8.8 hoping it would fix the problem. it didn't...
reinstalling didn't help at all, nor did the downgrade to an older version.
but the rest works perfectly (manually changing the collections etc.). good job (well if it's going to work
)