same problem here.
I am on Max 6 with Win7 Professional 64 bit.
I've installed latest Csound but when i try to install csound~ i get a first warning about not founding Max5.
but then the process goes on until get stuck with this error "Error opening file for writing Cycling '74msp-externals_csound~csound~_double.mxe
Click Abort to stop the installation, Retry to try again, or Ignore to skip this file"