Trouble logging into SubDirectory sites after server migration. Can only log in on Main Network site

On our Network site, blog.d30.me, which we just moved to a new server, users can no longer log in at the sub-directory sites, like blog.d30,me/mmichalakos

We can all log into the network page, but then have to run over to the individual sites.

I'm not sure what's different- we're looking at our wp-config file, and don't see any errors there.

Anyone got a strategy?