I've used WP MU for several years for one of my sites, but this is the first time I've run across this suite of problems. I've set up a new installation of WordPress an enabled the network. Set up the main site yesterday with no problems. The multisite network is configured to store additional sites in directories--we plan to point domains at the directories.
The main site:
The second site on the network (with problems):
The second site isn't showing any style sheet and the dashboard for the second site generates an error page that says: "The page isn't redirecting properly. Firefox has detected that the server is redirecting the request for this address in a way that will never complete."
It smells like a directory path problem. I've installed the proper network code in the wp-config.php and .htaccess files for the parent site.