I had a similar problem, that turned out to be related to Flash. No explanation for that, but that's what it was. Apple Engineering was confused by it, too.
In Finder open your system/boot drive in the left panel, and go to Library/Internet Plugins. If there's anything in there with "flash" in the file name move it to Trash.
Try CB again. If that didn't fix the problem, you can Put Back the files you deleted.
No guarantees — you may have something else going on.
You could also delete everything from Internet Plugins, and if that solves the problem, put the deleted files back one at a time until you find one that causes the problem. Then just trash that one (or two). It could be some other Plugin than Flash …