Loading development environment (Rails 2.1.0)

c:/ruby/lib/ruby/gems/1.8/gems/rails-2.1.0/lib/commands/console.rb:34:in `exec': Exec format error - irb --noreadline 
-r irb/completion -r "C:/Users/paul/Documents/NetBeansProjects/RailsApplication2/config/environment" -r console_app -r
console_with_helpers --simple-prompt (Errno::ENOEXEC)
        from c:/ruby/lib/ruby/gems/1.8/gems/rails-2.1.0/lib/commands/console.rb:34
        from c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
        from c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
        from script/console:3


if I get the line it's talking about :  

exec "#{options[:irb]} #{libs} --simple-prompt"

it gives me  :  
irb --noreadline  -r irb/completion -r "C:/Users/paul/Documents/NetBeansProjects/RailsApplication2/config/environment"
-r console_app -r console_with_helpers --simple-prompt

pasted in a command window when I'm in the C:/Users/paul/Documents/NetBeansProjects/RailsApplication2 directory works fine.

Have tried it under a normal 'admin group' user and under 'run as administrator' and get same error.

All plugins are latest

Product Version: NetBeans IDE 6.1 (Build 200805300101)
Java: 1.6.0_06; Java HotSpot(TM) 64-Bit Server VM 10.0-b22
System: Windows Vista version 6.0 running on amd64; Cp1252; en_AU (nb)
Userdir: C:\Users\paul\.netbeans\6.1


JRuby and Rails Distribution Plugin
Version: 0.103 Source: NetBeans IDE 6.1 (Build 200805300101)  
Plugin Description
Bundled distribution of JRuby 1.1 and Ruby on Rails 2.0.2

Ruby and Rails Plugin
Version: 0.103.2


*** LOCAL GEMS ***

actionmailer (2.1.0)
actionpack (2.1.0)
activerecord (2.1.0)
activeresource (2.1.0)
activesupport (2.1.0)
fxri (0.3.6)
fxruby (1.6.16, 1.6.12)
hpricot (0.6)
log4r (1.0.5)
rails (2.1.0)
rake (0.8.1, 0.7.3)
sources (0.0.1)
win32-api (1.1.0, 1.0.6, 1.0.4)
win32-clipboard (0.4.3)
win32-dir (0.3.2)
win32-eventlog (0.4.8, 0.4.6)
win32-file (0.5.5, 0.5.4)
win32-file-stat (1.2.7)
win32-process (0.5.9, 0.5.3)
win32-sapi (0.1.4)
win32-sound (0.4.1)
windows-api (0.2.3, 0.2.0)
windows-pr (0.8.7, 0.7.2)