Thanks for sharing the solution to your issue.
CB integrations setting in CB Login module allows CB plugins to add content into the login module.
Only core team CB captcha and CB profileBook use that feature, and doesn't add any javascript to the mix.
So it must be due to another third-party CB plugin.
It would be interesting to know which 3pd CB plugin does that, so the devloper can be informed. To do that unpublish one by one the 3pd CB plugins and check with which the JS error goes away.
what IE version was it ?
what JS error did you get ?