Hmmm an interesting Samba questions

I have a small network running Samba. On one of the Samba shares, I have installed an old DOS program which the users work on. Since their transition from WinNT to Samba they have been complaining that although on WinNT they could all work on the same program and they could all insert data, now only one at a time can make new records in this old program.

From the way I understand it, the inserting of data is a menu which prior to Samba, many users could be using simultatenously but now cannot any more.

Can someone tell me if there is a way to overcome this problem? Many thanks Chris