Inventor 5.3 Exporting to .Dxf

[scott_d]

Hey,
Hopefully there are some Autodesk Inventor users out there, Because my and my teachers are stumped!
I have drawn a part in Inventor 5.3, and we need to export it in .Dxf format so we can mill it on our small mill at our school.
The problem is, we dont know how. We have followed the directions in the help file, and it acts like it is about to do it, but nothing happens.
It seems like when we go to "save copy as", there should be a file option for .dxf, but there is none. So, if you were to type it in at the end, then click the option button off to the side, it gives the export options for the .dxf file. We can go throught the steps, then click finish, and it does nothing.
We are running windows 2000 pro.
Thanks for any help