Cannot open files unless they have the extension in the name using SMB
instead of AFP

I am running a Mac OS X 10.3.2 connecting to a Win 2000 server using
SMB instead of AFP. SMB is much faster and our IT department wants to
phase out Appleshare altogether. The problem, when I use SMB, is that
I cannot open files that are missing their file extensions. So I have
to go to the file I want to open and then add the extension, then go
back to the application and open the file. When I use AFP the files,
without file extensions added to their name, open fine and are
recognized.

We have thousands of Quark documents and they do not have file
extensions as well as graphics and text documents. What are we missing
here, is there a way to fix this problem without having to add the
extensions to these files?

Thank you,

Dave