I am running WordPress MU 2.9.2 and Buddypress 1.2.3. I am using Anti-Splog to prevent (or at least slowdown) the spam blog creation. I have Anti-Splog set to move the wp-signup.php page because I was still getting spam blogs that Anit-Splog wasn't finding.
I am having problem with blogs other than the main blog accessing the register page. They give a 404 error. All of the themes available to our users are from the Themes 133 pack.
I've attached screenshots of the plugins used on the site.