Redmine

Hi
I am very new to this system.
I am setting up REDMINE on Win XP SP3 machine following the setup procedure avaialble at http://www.redmine.org/projects/redmine/wiki/HowTo_Install_Redmine_in_a_sub-URI_on_Windows_with_Apache.
I have reached the section Install RedMine. And I started getting errors from the section 6 under Installing RedMine. When I issue the command rake generate_session_store I am getting the error message as shown below:
C:\Webserver\Redmine\redmine-1.0.4>rake generate_session_store
(in C:/Webserver/Redmine/redmine-1.0.4)
rake aborted!
uninitialized constant ActiveSupport::Dependencies::Mutex
C:/Webserver/Ruby/Ruby187/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2383:in
`raw_load_rakefile'
(See full trace by running task with --trace)

I tried to issue --trace and I am not able to make it out.

I would gretaly appreciate it if someone could assist me in getting me to come out of this error proceed with the REDMINE setup.

Regards
JJohn