Ok, in the cmd.exe window type in
ipconfig /?
And hit enter. It shoudl list the things ipconfig supports. I know it supports /all, I use that myself, but I am curious what yours will report.
I have attached a screen of what it says on my XP system in vmware.
Also lets do a search for any ipconfig file on the system to make sure you dont have a duplicate that might be getting in the way. I attached a screen shot of how I want you to do the search.
I also attached the two ipconfig files from my system32 folder. Try replacing yours with these and see if it helps

Shane