|What you describe isn't going to a cmd prompt. You are just typing ipconfig in the run line.|
Follow this sequence
Go to Start and Run
type in cmd and hit enter
in the black box type ipconfig
This is how you usually do all command line utilities. You go to cmd first.
If under these circumstances you still have the same results do a ipconfig /all >test.txt and then read what the file test.txt says for a ipconfig error