The Dink Network

Could just be the machine, or something else you've put in your Dmod that makes changing the midi's take a lower priority. Some downloaded midi's also have a pause at the start of the .mid file before the tune actually starts, thats also possible.
If you've finished your mesh and added pictures of it to your Dmod as a sprite or something, for example, you need to maake sure the graphics are in the Dink pallet. Unless you want to restrict users to Truecolor mode.