I had this same problem also
I installed dotLRN 2.1.0 Final on PG 7.4.6 without any error.
The first admin user did not have permission to portal_read_portal and also he couldn't customize layout before the first server restart.
One more problem I encountered so far is that i couldn't delete a survey, the server gives:
Database operation "0or1row" failed (exception NSDB, "Query was not a statement returning rows.")
