Ah - so the SB hardware is on the motherboard? So (really just thinking out aloud here, but it might give you or me some ideas...) windows has disabled it, but a DOS app. might get confused as it might be seeing two sound cards.
One idea : do you have an icon which you use to start PS1.3? Try bringing up it's "properties" page, click on the Program tab, click on advanced, then click on MS-DOS mode. This will cause your computer to reboot into pure MSDOS mode to run PS1.3
When you exit PS1.3, your computer will boot back into windows.