Just another thing: Some people said they installed Python 3.x. That doesn't mean that your system or Reaper use this new version. There's a default version installed with the system (for OS X it's 2.6), and you may install many additional versions; but you got to change the system default or tell Reaper to use a different version. (See this post by schwa:
http://forum.cockos.com/showthread.php?t=83968 )