Can't reach dashboard for new sites in MultiSite

I upgraded to WP 3.9 on one site, (should have known better!), and now I can "start" a new site - but can't get to it once it's been "created".

So, I put a fresh install of WP 3.9 Multi-Site on another domain - same thing there.

I've done all that is necessary with wp-config and .htaccess - I still can't reach any sites that I create. Everything seems to be working fine otherwise. AND YES - I did the Wildcard DNS things too.

Thanks in advance,