When creating files from scratch with Jazz++, I don't have any problems, but when trying to edit midi files created by any another sequencer (specifically pieces by other composers), most or all of the tracks will only play the Piano 1 patch (Microsoft GS Wavetable synth patch #00). This occurs even if I don't make any changes to the file, e.g. I open up the file, save it, and close it again. The file plays fine as long as I never save any changes I edit.
Note that this doesn't necessarily occur with Windows Media Player, but with other midi players such as the Java SDK player, i think, and GameMaker 8.1's built-in midi player. I am using the Microsoft GS Wavetable synth, and don't wish to change this.
The attached file is a midi piece from vgmusic.com. Listen to this file, then try opening this file in Jazz++, save without making any changes, then importing it into GameMaker 8.1 (the Lite version is free; info and download links at the official website: http://yoyogames.com/gamemaker/windows ). When you listen to it in GameMaker, most of the tracks only play piano.
Given this info, can you guys tell me what I'm doing wrong? I'm not very knowledable about midi (without Jazz++ I'm helpless) so maybe my configurations are set up wrong?
Test file: "Koopa's Road" from vgmusic.com