##Error Log
Processing UsersController#login (for 127.0.0.1 at 2009-04-27 17:13:35) [GET]
Rendering template within layouts/users
Rendering users/login

ActionView::TemplateError (You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.[]) on line #2 of app/views/users/login.
html.erb:
1:  <!-- app/views/user/login.rhtml.erb -->
2:   <% if @flash[:message] %><div><%= @flash[:message] %></div><% end %>
3:   <% if @flash[:error] %><div><%= @flash[:error] %></div><% end %>
4:
5:   <%= form_tag :action => 'process_login'

    app/views/users/login.html.erb:2

Rendered rescues/_trace (57.0ms)
Rendered rescues/_request_and_response (0.0ms)
Rendering rescues/layout (internal_server_error)

##login.html.erb
 <!-- app/views/user/login.rhtml.erb -->
  <% if @flash[:message] %><div><%= @flash[:message] %></div><% end %>
  <% if @flash[:error] %><div><%= @flash[:error] %></div><% end %>

  <%= form_tag :action => 'process_login'
%>
   Username: <%= text_field "user", "username" %>&#x00A;
    Password: <%= password_field "user", "password" %>&#x00A;
    <%= submit_tag %>
  <%= end_form_tag %>

##UserController
  class UsersController < ApplicationController
    def login
      @user = User.new
      @user.email = params[:email]
    end

    def process_login
      if user = User.authenticate(params[:user])
        session[:id] = user.id # Remember the user's id during this session
        redirect_to session[:return_to] || '/'
      else
        flash[:error] = 'Invalid login.'
        redirect_to :action => 'login', :email => params[:user][:email]
      end
    end

    def logout
      reset_session
      flash[:message] = 'Logged out.'
      redirect_to :action => 'login'
    end

    def my_account
    end
  end