Error with running 'rake migrate'

when I run (under dev…/trunk/www): rake migrate, I get the error:
rake aborted!
Syntax error on line 36, col 2: ‘host: localhost’

when I run (under dev…/trunk/www): ruby script\server, I get the same
error msg with:
c:/ruby/lib/ruby/1.8/yaml.rb:133:in ‘load’:

help !?!

Your database.yml might be corrupted or have invalid characters.
Ensure that you don’t have any tabs in that file.