Windows Vista Lost DOS command in Vista

Every time I type a command in a dos window (i.e. ipconfig), I get an error that the command is not recognized as an internal or external command.

Any ideas as to why I would be getting this? These were working when I first upgraded to from XP to Vista.

 

Well I guess I should have waited until I had done a reboot to post this message. I guess what happened was that I had both my wired network and my wireless network connected and when I disabled my wireless card is when I lost my DOS commands.

I couldn't do ipconfig, net use, nslookup which all have to do with having a network connection. When I disabled my wireless card, my system was still thinking that I was now disconnected from the network.