cmd.exe

Hello all, I have a W2K Pro computer on my network, and a strange thing happen when I try to use command lines from the DOS-alike window. For example, I want to type ipconfig /all and I get the response: 'ipconfig' is not recognized as an internal or external command,operable program or batch file. And that is happening for all the line commands I trying. What's trickie, is that if I use the same commands from start>run and type the command, they work.
Anyone knows what should I do to get out from this mess? Thank you in advance for any answer.