Thanks Zero - I have the same folder on an old Creative Zen - no problem. It gets hairy when I put the album onto my Samsung Galaxy Player 5.0 or my Kyocera Rise (which I bought to take over for the Zen - got it cheap). So to me, it seems to point to the Android OS. I've even downloaded the DoubleTwist player app to see if it might just have been the Google Play Music app - but to no avail. Still the same result. Frustrating.
On my PC, I just copy the file over to the album folder and then when I'm happy and all the ID fields are as I want them, I just copy it over to the SD card on either player. When I finish copying, I 'explore' the card and everything is under one folder. It's only when I put the card back into the device does it screw up.
I do have Winamp but I'm not sure that would be the solution although it's getting to a point where I just may try it. I just figured that the ID3 Tag would do just as good a job of editing.