Bulk updating Gem source index for: http://gems.rubyforge.or

Hi all,

I’m having a bit of a problem with installing ruby on rails using gem
on Windows XP. after
gem install rails --include-dependencies
it say as follows

Bulk updating Gem source index for: http://gems.rubyforge.org
ERROR: While executing gem … (Gem::InstallError)
invalid gem format for c:/ruby/lib/ruby/gems/1.8/cache/
actionpack-1.13.3.gem

Any idea what I’m doing wrong here?