[NTG-context] Error message in texexec --make --all

Hi, I'd like to use the stand-alone-version of ConTeXt with Win2k, but it doesn't work: F:\isoimage\usr\local\context\demo>texexec --make --all f:/isoimage/usr/local/context/tex/texmf-local/scripts/context/ruby/newtexexec.rb:8:in `require': No such file to load -- base/switch (LoadError) from f:/isoimage/usr/local/context/tex/texmf-local/scripts/context/ruby/newtexexec.rb:8 but f:/isoimage/usr/local/context/tex/texmf-local/scripts/context/ruby/base/switch exists and contains the required file(s). What's wrong with my installation or batch-file? TIA, Stefan .