Originally Posted by kovidgoyal
calibre doesn't mount your device or unmount it on OS X. That is handled by the OS, so your problem is not related to calibre.
Seems like it is. It only happens after I've used Calibre, and only with the latest versions. I am able to unmount the reader from the Finder normally if Calibre hasn't been opened. If I use Calibre 0.5.1 it works okay.
What it looks like to me is that Calibre isn't fully releasing the volume after use. From the other thread I saw, it sounds like in Leopard you get the "in use" warning (no crash, though the volume can't be ejected) but in Tiger the Finder just dies.