As requested, here's my comment transferred into an answer. I suggested reinstalling Leiningen because apparently a broken Leiningen installation was the source of the problem.
As a little background explanation, I'm using Leiningen on both Linux and Windows, and I've made the experience myself that the primary method for installing Leiningen recommended on its homepage, the lein
resp. lein.bat
script, just works, whereas the alternative
installation methods (Linux package managers, Windows installer) often produce broken installations.