Hi Tim,
There's a revised version of the driver that will be coming out with the next release of calibre (0.7.2) sometime this weekend. You can wait to see if things work under 0.7.2, or you can send me a debug trace.
If you want to send me a debug trace, open a command window, then type this invocation:
When things grind to a halt, copy the contents of the command window and post it here in a reply.
Please include your OS and the language of your iTunes installation.
G