[Rails] reverting to rails 2.3.3

Hi All,

sor some odd reason i updraded my gems, which updated rails from 2.3.3
to 2.3.5.

I now have issues:

/usr/local/lib/ruby/site_ruby/1.8/rubygems.rb:270:in `activate':
undefined method `map' for nil:NilClass (NoMethodError)
from /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:
35:in `require'
from /Users/westy/apps/ruby/piste_buddies/vendor/rails/railties/lib/
commands/server.rb:1
from /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:
31:in `gem_original_require'
from /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:
31:in `require'
from script/server:3

i'm assuming it's to do with the update, so i need to know if anyone
can advise me on how to revert it from 2.3.5 back to 2.3.3 (daft
question i know)

can anyone suggest what this issue means? Google hasn't been much help
so far, though i'll keep plodding.

thanks