gem cache goes to wrong drive in windows if ruby is run from non C drive: http://rubyforge.org/tracker/index.php?func=detail&aid=23429&group_id=126&atid=575 on windows platform, RubyGems generates a gem.bat that can't execute: http://rubyforge.org/tracker/index.php?func=detail&aid=24039&group_id=126&atid=575