I'm not sure if there is a similar bug with WordPress MU with other TLDs, but when I intstalled WordPress MU (not just once--four times), there was a recurring error when the config tables were created. Instead of "http://infinite9.net" it came out "http://net/infinite9/", in the config table. Thankfully I had enough knowledge to search out this bug and fix it for my own install, but I wouldn't even begin to know what causes the error in the install.
BTW: If anyone else gets this error, open up phpMyAdmin, search for the table "wp_1_options" (where "wp_" is your table prefix) and browse through until you find "site_url", and enter your domain name, MINUS the www. and no trailing slash.
-Hope that helped,
Ashley
(http://www.infinite9.net)