yeah the origional thread on the atari forum is talking about vista i have windows seven. I tried the notepad option but that did not work either. opening the note pad file launches dos but the same error comes up. Stinks!
Have you considered using VMware Player?
I think that it is still free (you may have to sign up though).
https://my.vmware.com/web/vmware/evalcenter?p=player&ei=utf-8&fr=b2ie7
VMware Player - Download.com
I created an XP VM and installed my (old) games in it.
I think it's been re-named dplayx.dll since Vista.
You can find it here: C:\Windows\SysWOW64
I also found the reference below for the same problem. It suggests copying the file and naming the copy dplay.dll
dplay.dll issues
cool found the file copied and renamed and it works but it does look like there is more to it like disabling windows or something. Which of course I do not know how to do. I might try and play it like this anyway for now.