On Windows 2000 server: $ irb irb(main):001:0> require 'Win32API' => false irb(main):002:0> thread_id = Win32API.new('kernel32.dll', 'GetCurrentThreadID', [], "L") RuntimeError: GetProcAddress: GetCurrentThreadID or GetCurrentThreadIDA from (irb):2:in `initialize' from (irb):2:in `new' from (irb):2 This happens both with the cygwin and the one-click installer of Ruby. Trying to get GetCurrentThreadIDA gives the same result. Am I doing something wrong? Guillaume.