I wish I could offer a proper explanation, but I don't know enough about the current versions of the cmd.exe (or command.exe?) shell and how they handle redirection or pipes -- let alone how they do this when the first word on the command line is the name of a perl script.

Just for grins, what if you use a windows port of the bash shell instead?

Also, I'm curious why would you use a system call to run "dir", rather than using the perl-internal "opendir...; readdir..."?

Or, if you're really committed to the idea of using a system call to run "dir", have you tried doing the redirection within the system call? (Would that work from the ms shell command line?)