Part 1 is to chdir \Ruby\bin and delete the five *.bat files

Part 2 is to (still in \Ruby\bin) rename ri to ri.rb, rdoc to rdoc.rb, 
erb to erb.rb, irb to irb.rb, and testrb to testrb.rb.

Part 3 is to chdir to \Ruby\lib and execute rdoc -R

Unfortunately, that part is still broken, and will eventually crash. 
But it will leave you better off than you were before.

-- 
John W. Kennedy
Read the remains of Shakespeare's lost play, now annotated!
http://pws.prserv.net/jwkennedy/Double%20Falshood.html