Comment 1 for bug 1123210

Sorry for the late reply.

Please try below steps.

1. Call from command prompt
You can launch Checkout/branch dialog via command line.
Please try this command, and tell me if message or traceback are shown.
$ tbzrcommand --command getnew

2. Disable bzr-svn
According to your another post, bzr-svn may have some trouble.
If you can, please remove svn folder from Bazaar\plugins, and try again.