What OS (yes I know it is a Windows variant), version of nmake and version of Perl are you using?

The trite answer is: "The command line is too long", but NT based OS'n should be able to handle 32K long command lines so the implication is that the version of nmake or Perl you are using can't cope. The line given is about 3500 characters long. My Pick is that nmake is choking.