by Colin Fraser.
Whatever advice could be given here is most likely going to be wrong. This is not because the advice is bad, but you have not provided any sort of information about your Moodle. Different OS', for example, have different ways of handing errors. This one though, I suspect is a permissions error. That is, you have not set the database up properly, or included the appropriate password. Check you root password, my bet is there - but it could be a loser.