This is a brand spanking new completely clean install that I have not even been able to look into the admin let alone try to add any themes or plugins.
I have done everything on the codec page about login troubles and none of it fixed the issue.
Basically, it completed the install, gave me the button to go to login, I did so, entered the admin user name and password chosen by me during install. The screen refreshes back at the login form. Re-enter a few times to be sure I got it right, do the forgotten password thing, do the database hack to set the password again with an MD5 yadda yadda yadda - got the T-shirt (and the password reminder emails).
polite version - it's broken !!!
(that is not at all what I want to say is its condition).
Remember this is a brand new fresh install, made from an uploaded file package that was downloaded off wp.org a few hours before uploading it to the server (an hour ago).
There is nothing in wp-config about any of the multisite configs or defines. There is no htaccess file in the root folder. After spending the last week trying to debug WP 3.0 multisites, it all looks rather bare and empty.
.... and I have no idea why it will not allow me to login to admin.
Anyone got any clues?