Monday, November 26, 2012I put this in the Galaxy S3 without formatting, restarted the phone and it showed 59.4g GB of space.  I transferred all the files from the old 16 GB card and then moved all my music to the card with the phone connected to my computer by the USB cord.  Still lots of space left and the various music players seem to see all the music.Tuesday, November 27, 2012The card didn't show up on the phone this afternoon.  No message, just no songs to play and no card according to everything I could check on the phone.  I restarted the phone and got a notification that the SD card was corrupt, needed formatting and that I would loose all data on the card.  I restarted the phone again, without formatting, and the card came up like it had never been missing.  I am writing this on Thursday, 11/29 and I have not had another issue with the card.December 6Well, I don't know what to think.  The card disappeared again and I reformatted it FAT32 in an attempt to fix the problem.  The whole point of getting this large card was to have my music on my phone and not have to stream it from the cloud.  I tried several music players and went with PowerAmp because of the good reviews and that I could specify the folder to play from.  So PowerAmp is looking for the folder /mnt/extSdCard/Music and playing the songs in all the subfolders.  It is PowerAmp that tells me that folder is not available.The card has gone missing one other time and restarting the phone fixed the problem.Today, PowerAmp would not play and when I got home I found the Music folder was gone.  I also had Ringtones folder and it was also gone.  Now, I may not be the sharpest saw in the shed, but I know I did not delete those folders.  The card had other folders but not those two so it had not been reformatted.I am starting to think the problem is with the Galaxy S3.  I had a 16 GB FAT32 card in this phone that had been in my previous HTC phone.  That card was not large enough to held my music so I don't know if it was disappearing or not.  I wish this combination of phone and 64GB card was more reliable but just don't know where the problem lies.I lowered the stars from 4 to 3 but I really don't know if the problem is with the card, the phone or both.  All I know is that they do not seem to be playing well together.December 7There was a notification on the phone this morning that the SD card was corrupted and needed to be formatted.  I restarted the phone several times and got the notification each time.  I reformatted the SD card using the phone, a step I don't think I have tried yet.December 8Another MINOR problem I have is that the message counter gets stuck on 1 when I have no new messages.  The only fix I have found is to restart the phone.  That happened this morning and I got the corrupted card message again, but restarted again and the card came up OK.December 11So, the files on the card keep disappearing.  The card is mounted and the phone shows the correct free memory but PowerAmp, and file directory programs do not see any files on the card.  I restart the phone and the files come back.  Very strange.  I played music on and off all day today without a problem and then this evening all the files disappeared again. Restarted the phone and all is well again.December 15My phone upgraded to 4.1.1 yesterday and the same issues remain.  It is a crap shoot as to if music will play.  I take a lot of photos and use the service Zenfolio to store and display them.  I have an app that syncs with Zenfolio and keeps a phone size version of the photos on my phone.  I set this app to store the photos on the Samsung SD card and have similar issues with it when the data on the phone goes away.  This morning the SD card came up as corrupt again after a restart to get the data back.  It took a total of 3 restarts to get the music and photos back.December 18I have been trying to play music stored on this card today and my phone has reset several times.  Very frustrating.  I ordered a SanDisk 32 GB Mobile microSDHC Flash Memory Card SDSDQ-032G-AFFP today for about $25.00 and I'll see if I have the same issues.  Very disappointing.December 28I purchased and installed theSanDisk 32 GB Mobile microSDHC Flash Memory Card SDSDQ-032G-AFFPand copied all the files from the 64GB card to the new 32GB card.  No formatting, no fuss, no muss.  I have not had a phone reset since, have played music through Bluetooth for hours in the car, have viewed photos.  Everything just works.  Half the memory but what I have is always available and the phone works, a good trade off.  I am still disappointed that the 64GB did not work with the SG3.  I have purchased aelago Mobile Nano II USB 2.0 microSDHC Flash Memory Card Reader (Black)to use the 64GB MicroSDHC card as a thumb drive.