Status: 500 Internal Server Error when running mongrel

Hello everyone! I try run simple RoR application, I go to RoR default "hello page",but I got error, when trying to open new views. Status: 500 Internal Server Error   could not open database: unable to open database file     C:/Ruby/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.2.3-x86-mswin32/lib/sqlite3/errors.rb:62:in `check'     C:/Ruby/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.2.3-x86-mswin32/lib/sqlite3/database.rb:79:in `initialize' .... and so on, long list

my database.yml is default: development:   adapter: sqlite3   database: db/development.sqlite3   pool: 5   timeout: 5000

But I am running almost the same configuration using Instant Rails without any problems/ Has anyone met the same problem?

Have you installed SQLite3?