This fix removes anti-spam/spoof protection in CB and is a workaround which doesn't solve the problem.
As already analysed during CB testteam session a few days ago (took quite a few hours actually), the problem seems to be as follows:
1) your site Javascript seems to have an error preventing the initialization code of CB to be executed;
2) it seems to reload or modify the page with different content, and this makes CB detect a session timeout.
Without being able to exclude CB 100%, it looks very much to be a bug elsewhere in your site, and it looks like when you unpublish SWMenuPro it works fine.
We couldn't go very deep in analysis, since the Javascript code of SWMenuPro is compacted, but have given the above information.
We hope a fix will be found soon.