[FormerPalmOS]

If playing back music from your SD card, check a) if you have caching enabled on the FATFS filesystem on the SD card and b) if you have SD power management enabled. Anecdotal evidence (i.e. not confirmed or tested) suggests (i.e. doesn't prove) that caching will reduce accesses to the SD card and improve the efficiency of those accesses and b) power management being enabled may contribute. I think the latter is very unlikely the cause, but is something you could easily play with to see.