Gem::RemoteFetcher::FetchErro when installing rails

I am trying to install rails on Ubuntu 8.10, and met following errors. Please help me get through.Thanks.

root@pierr-desktop:~# gem install rails
ERROR:  While executing gem开发者_如何学编程 ... (Gem::RemoteFetcher::FetchError)
bad response  500 (http://gems.rubyforge.vm.bytemark.co.uk/gems/actionpack-2.3.4.gem)

#other information 
root@pierr-desktop:~# ruby -v
ruby 1.8.7 (2008-08-11 patchlevel 72) [i486-linux]
root@pierr-desktop:~# gem -v
1.2.0
root@pierr-desktop:~# gem list

*** LOCAL GEMS ***

activerecord (2.3.4)
activesupport (2.3.4, 1.4.4)
daemons (1.0.10)
gem_plugin (0.2.3)
rack (1.0.1)
rake (0.8.7, 0.8.3)
wirble (0.1.3)

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You might just have to try again.
Looks like the server returned an error 500 which seems to be intermittent.