error 500 - cannot access dashboards or wp-admin for subdomains

(WP 3.0.4, BP 1.2.7)

i recently upgraded to WP 3.0.4, and had many an issue with permalinks. i sorted that all out, but there is an issue where nobody can access their dashboard (or login) via /wp-admin. As the super admin, I also cannot login to their backend via SuperAdmin | Sites | Backend.

If they go to their "subdomain".minblogs.com/wp-admin they receive an error 500

If they go to MinBlogs.com/wp-admin they get the login screen, but then it redirects them to minblogs.com and they have no access to their dashboard.

If I go to SuperAdmin | Sites | Backend for any subdomain, i get a blank page.

Any ideas?