Calibre suddenly won't launch on Lion

[eiscir]

Hello all, first post!

I wonder if anyone can help. Calibre's been working fine for me, until the other day when it started quitting after a few bounces in the dock (OS X v 10.7.2). No error messages pop up.

I had a hunt and came across this thread, which also links to this bug report.

I'm having the same problem, in that Console gives me the following information after an attempted launch:

23.01.2012 10:15:18.677 [0x0-0x65065].net.kovidgoyal.calibre: RuntimeError: Failed to load the usbobserver plugin: dlopen(/Applications/calibre.app/Contents/Frameworks/plugins/usbobserver.so, 2): Symbol not found: _FSMoveObjectToTrashSync
23.01.2012 10:15:18.677 [0x0-0x65065].net.kovidgoyal.calibre: Referenced from: /Applications/calibre.app/Contents/Frameworks/plugins/usbobserver.so
23.01.2012 10:15:18.677 [0x0-0x65065].net.kovidgoyal.calibre: Expected in: dynamic lookup
23.01.2012 10:15:18.736 com.apple.launchd.peruser.501: ([0x0-0x65065].net.kovidgoyal.calibre[608]) Exited with code: 255

Trouble is, Calibre works fine on another user account on my machine, and I never did anything between Calibre working and Calibre not-working that could cause it not to find _FSMoveObjectToTrashSync. How can I just point Calibre at the symbol, which is obviously there, and not outdated or corrupted?

Thanks in advance
Tom.