Command Prompt - Missing commands

Okay, I know this is propably the wrong forum, but I can't find any forum to suite my question better, and leaving it in Off-topic also feels wrong. Please move to where it belongs, it's a Windows (= software) question.

The problem is, my Command Prompt doesn't want to listen to my "ipconfig /all" command, so I tought "What, that's odd" and went with "help". No luck, neither of these are recognized by the program, nor are the "ping" command.

However, the cd, mkdir etc. works all right.

Also note, I've recently installed devkitPro, and nor does the "make" command work (I tried to compile a DS homebrew to a binary). But I hope it isn't devkitPro that has messed around with my CMD.

Thanks,
FireFly.