Error: NameError (uninitialized constant Mysql)

Hi

I am getting this error on my localhost in a project I started work on.
It was working properly until sometime back. I am not what broke this
because I had to do some copy paste from some other project to make it
deploy on site5.

NameError (uninitialized constant Mysql):
d:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:123:in
const_missing' d:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:133:insend’
d:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.3.1/lib/active_support/dependencies.rb:133:in
const_missing' d:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/connection_adapters/mysql_adapter.rb:34:inmysql_connection’
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/connection_adapters/abstract/connection_specification.rb:251:in
`send’…

I have installed rails in the app/vendor folder. I am getting this
problem on my localhost only. After deploy its working fine. I am tired
looking at this errror all day.

thanks in advance

Rajesh