Can not install 3.7.1- Could not copy wp-includes/class-simplepie.php

I am running a website, using the theme Marla. I tried doing the automatic install, and five times it’s told me the installation has failed because it could not copy wp-includes/class-simplepie.php. I can not find any issues about it so it might just be my machine, or maybe I’m doing something wrong. The update should work with the, as the autoinstaller supports all versions above 2.7. If I could get some help here, that would amazing. It’s rather frusturating, and neither I, nor the fellow admin with me can figure it out.