I have a Zumo 450 and use it as an MP3 player ( connected to an audio amplifier ) and have a question. I load my SD card with about 600 MP3 files and I can listen to them as I ride, only problem is it takes about ten minutes for the files to be read. So for the first 10 miles I can't play them on the Zumo. Is there a trick to loading my SD card? Should I use folder and sub folders or what is the best way to handle this problem? Thanks.