I tried to reformat using the recommended FAT32 file system and trying both format options. These didn't work for me. After further digging around of various posts, I remembered that the USB I was trying to use was temporarily used as a Windows boot-up USB and that it's Master Boot Record was written for this.
My solution was to use DISKPART, a disk partitioning utility that comes with Windows. I stumbled across the link http://www.wikihow.com/Make-a-USB-Bootable and thought that it may work if I followed the instructions up to the point where I would install the OS onto the USB.
If you do this, you will need to be very cautious. I don't think it would overwrite your Windows OS partition but please be careful. The basic steps I took: I cleaned the USB (removed its partition), created a new primary partition, and formatted the partition to FAT32 file system, and then copied my music files back onto the USB drive.
Here are the details for the steps I took:
- Open a command prompt as Administrator
- Start DISKPART from there; type it in + hit enter.
- Type in select disk N + enter where N is the USB drive. You may have several partitions on your laptop or PC so this is where you need to be careful. It's most likely the highest numbered N in the listing. If you have any doubt, please stop here.
- Type in clean + enter. I had to do this twice since it gave me an error the first time. Once you see the DiskPart succeeded in cleaning the disk message, you can go on.
- Type in create partition primary + enter.
- Type in select partition 1 + enter.
- Type in active + enter.
- Finally, type in format fs=fat32 + enter.
From there, you can copy your MP3 files to the drive. If you want to be sure before you spend a lot of time copying a bunch of files, you can copy a small folder, go test it in the car, and then continue from there.
Good luck. I hope this helps someone as it did for me.