title: what does 'invalid gem format' mean?
body: <p>Does this mean I've hosed my ruby/gem/rails environment somehow? I've been using InstantRails2-0 happily for awhile now, but recently decided to upgrade rails. It has been a major pain so far. First I had issues getting the latest gem version, rubygems-update couldn't get the latest. I was finally able to get the latest gem version by manually downloading it and running setup.rb for rubygems-1.3.5.</p>
  
  <p>When I do '<code>gem update rails</code>', I get the following error:</p>
  
  <p>invalid gem format forr C:/ruby/lib/ruby/gems/1.8/cache/activesupport-2.3.5.gem</p>
  
  <p>I tried manually downloading the activesupport gem and doing 'gem install local [path to gem]'. This appeared to work, so I did the same with rails 2.3.3.gem, but then got the same invalid gem format error, but for activerecord-2.3.3.gem.</p>
  
  <p>My gem version is 1.3.5. Current rails version is ....not working anymore because of RubyGem version error: activesupport(2.1.1 not = 2.0.2)</p>