If you clear your cookies (logging you off of the site) after the banner "X new answers to this question" appears, a blank error messages comes back when you try to vote on an answer.
It appears that the answers load properly, but when you try to vote on them, you get this:
- View any question, wait for an answer to be submitted to get the new answer banner to load.
- Remove your cookies for the site you're viewing (can be easily done in FF by clearing your history).
- Load the new answers by clicking on the banner.
- Try to vote on one of those new answers.