Nobody else having this sort of issue? Hmm, guess I'll file a bug report.
i'm also having this problem! good to find a mate, anyway.
https://moodle.org/mod/forum/discuss.php?d=214257#p933395
I tried everything I could find in the forums too (change mnethostid to 0, reset guest password from salt in config.php, ensure guest autlogin checked) and still cannot login to the site as a guest. Using Moodle 2.3.2.