WordPress MU

I've got a MU installation with a number of subdomain-based blogs, and I'm having an issue with one - and only one - of them. So my situation is this... I expect and get:

go to http://www.rootdomain.com/wp-admin/
get http://www.rootdomain.com/wp-login.php
enter user/pass
get http://www.rootdomain.com/wp-admin/

but what I also get is:

go to http://www.minordomain1.com/wp-admin/
get http://www.minordomain1.com/wp-login.php
enter user/pass
get http://www.minordomain1.com/wp-admin/
...works dandy, and yet...
go to http://www.minordomain2.com/wp-admin/
get http://www.minordomain2.com/wp-login.php
enter user/pass
get http://www.rootdomain.com/wp-admin/

Clearly I've missed something or messed up something in the DB, but I can't find the missing entry... the wp_sitemeta, wp_##_options, wp_site tables all look fine and parallel between the two minor domains. Same behavior regardless of user, so I don't think it's the site_admins setting. And as a sidenote, I did remove the 'www' domain restriction, they're all working. I also traced the browser requests and it looks like it's authenticating correctly, redirecting to http://www.minordomain2.com/wp-admin/ but then that call is the one redirecting to http://www.rootdomain.com/wp-admin/ ... and it's not changing a target for the form in the source on the login page, checked that.

Any suggestions of where to look next? I've been searching for hours and am pretty frustrated at this point...

Thanks in advance!

Anyone with any insights?

So are the secondary blogs mapped domains?

I've never used mapped domains - these sites are altered directly in the database, as of the old 1.3.x multisite methods. The weirdest thing is that I have 6 domains active in wp_site and five of them are working fine. I cloned this sixth one at the same time and (as far as I can tell) used the same methodology in editing the records.

I would have expected the wp-login page to be where the redirection would be happening, not after it authenticates successfully and then redirects to /wp-admin/ -- that's the confusing part to me.

Sorry, I'd never used the terminology of 'mapped domains' but apparently it's the same thing as what I think of as multisite, at least according to the writeup on bui4ever so I guess yes. I'm just not using Donncha's new plugin to do it which is what I thought you meant...

Just a suggestion:
Try logging out of main site and subdomains, clear cookies.
Or, try using a different browser so that there is no history/cookies.

Good call - and now I feel really dumb. Apparently I was logged in as a MU user with no permissions on that site and was being redirected from there... with no cookies/login it seems to work. Thanks!