Thanks for the quick reply enigma-2!
I found that having about 1800 songs divided up into directories (mostly alphabetically by genre) was a much easier way to browse them.
I have an identical SD card on the boat, and it plays fine on that sound system, but won't play in the Edge. And the one in the Edge plays just fine on the boat.
Another quirky thing the Touch system does is it tends to "reset" itself occasionally. For instance, our daughter likes purple, so I set the ambient lighting to purple, but after awhile it reverts itself back to the light blue, so I change it to purple again.
I'm tempted to do a full system reset, which I probably should have done when I bought the Edge, but I'm afraid I might lose my Sync and Sirius settings, so I'm hoping that would be a last resort ... ?