I recall that you had issues installing before - I guess those have been solved?
Could the scheduler issue be fallout from the failed install, where some data had been written
to the DB, but perhaps not fully?
Are you running a single server or multiple?
I understand your first paragraph that the server is up and you can log into the UI, but in it the RHQ server shows as unavailable?
Did you check that the page view interval is set to e.g. last X units and not to a fixed value some time in the past?