Type or copy http://geocities.com/smsrpg1/play_BAM.zip into your browser to download the zip file. After extracting (unzipping) its contents, drag and drop ONLYLOVE.BAM onto PLAYBAM.EXE. Wait till "Only Love" starts playing. If it works, press [Enter] to stop the song (or keep listening to it for a while if you wish), and then close the DOS window. Now try running smsrpg2.exe again.
BAM files are pre-MIDI music files. For some reason, the method described above works, though I'm not sure why. If you can't hear "Only Love", restart your computer, and try again.