I got a Motorola Droid from Verizon in the spring. It came with a Sandisk 16gb card, but I have over 20 gb of music, so for the time being I've only kept some of my music on there. I always transferred music through the USB connection, using Windows Explorer (I have Windows 7). I have all the files tagged with title/artist/album etc. but for easy organization I have them sorted into folders - a folder for each artist, and a subfolder for each album. Right now my phone is running Froyo (Android 2.2). My husband recently bought me a Samsung 32 gb micro SDHC card that he got on eBay. So of course as soon as it was in the phone, I wanted to transfer my music. I connected it to the computer via USB, and copied all my music folders onto it. Explorer showed that it would take a few hours for the transfer, so I left it plugged in overnight. The next morning it seemed to be complete, so I disconnected the phone and started up my music player. To my surprise, it only showed 4 artists. I went to Settings --> SD Card & Phone storage. It showed over 20 GB used. I plugged the phone back into the computer, and it again showed up as a drive in Windows Explorer, and it showed that all the music was there. But it wasn't showing up on the phone. When I got to work, I tried plugging it into that computer, but now Windows Explorer only showed those 4 artists. I later noticed that the 5th artist folder had an album name with an apostrophe in it, which was reflected in the folder name. I wondered if there was a problem with non-alphanumeric characters so I combed through all the folders, removing anything that wasn't a letter or number. I tried copying over just a few at a time, but still, once I looked at the phone, not all the songs were there. My husband suggested formatting the card. On the phone, I tried to unmount it, and the screen said "unmounting in progress" but never finished, so I was not able to select the format option. My husband then took the card out and formatted it from the PC, as FAT32. I then tried just copying over the first 5 folders. Then I looked at the music player. Two artists were completely missing. Most of the others came over okay, but several of them (from different artists/albums, seemingly randomly) came up under "unknown artist" even though they are all fully tagged. I don't really know what to do. My husband thinks that maybe the Samsung card has some file format restrictions, but I'd hate to think I have to go through thousands of music files and eliminate all non-alphanumeric characters from the file names. I'm not sure why this problem didn't happen with the previous card, which was from Sandisk. I've checked this forum and Googled, and I can't find anyone else who's had this problem. Can anyone advise?