[Galaxy S III Q&A, Help & Troubleshooting] FailDeadly:
I'm using a GS3 w/ a Sandisk 64GB microSDXC card formatted as exFAT. I'm hoping someone here with knowledge of exFAT can help me troubleshoot an issue I've seen. This is probably going to end up fairly detailed, so bear with me.

I recently copied ~40GB of data to my new 64GB card in Windows using the card reader in my laptop. It appeared to go off without a hitch. Today, however, I noticed an issue with my music files (mostly .mp3 and .wma). I had transferred a new song to the card and it seemed to go through. However, on the device, the file didn't appear. So I did it again, transferred the file, and it seemed to go through. It didn't tell me there was a duplicate file on the device either, so I played it on the card through Windows to test it. No issues. Unplug my device and the file disappeared again.

So I go into ES File Explorer (and later I used the My Files application that Samsung loads, with the same results) and go into my music folder to see what's going on. It appeared that at some point, the file name got corrupted and concatenated with part of another file name; instead of being "artist - song.wma", it was "artist - song.wmas Track).wma". So I think that the OS doesn't like the .wma in there, and try to rename it to what it should've been. The system says that that the file system already exists. I tried to delete the file, and it won't let me. The file explorer is also reporting that the file is 0kb in size. At this point, I open up a terminal emulator and try to delete the offending file through the command line, but I cannot delete/rename the here either, despite being listed (I'm told the file does not exist). Finally, I plugged in back into my Windows box but the bad files will not even show. The file on my computer is good and plays fine.

So I scratched my head for a little while. Then tonight at the gym I wasn't able to find the song I wanted. Sure enough, it was tied to this issue. I went back into the file explorer and found ~50 files (of ~4200) that had corrupted file extensions. These differed from the original in that only the file extension had been altered (ie .mp3p3 or .wmaa). However, I am unable to delete/rename any of the files. Also worth nothing is that some of these files had sizes. It's possible that other files exist like the original where the file extension is valid, but the original file extension is within the file name.

I have not confirmed this yet, but it is also possible that the issue is not limited to music files. I was looking through my pictures the other day and noticed that some images weren't loading; I deleted these files at the time and didn't think anything of it because a few weeks back my epic 4g corrupted my microSD and I had used some file carving tools to recover some images (obviously, not a perfect fix).

So the problem is beyond my expertise at this point. I'm not sure how to handle these damaged file remnants. I'd like to get rid of them because they prevent the existence of the good file in that particular folder in addition to taking up space. As a short-term solution I re-copied the files I wanted to a temporary folder on the card and they are working without issue.

Right now I'm leaning towards wiping the card, reformatting it, and transferring again. However, before I do that, does anyone have any ideas? Is there any chance this could be an issue with the card itself? Or a GS3 issue? The files on the computer are still good and the problem seems to manifest itself regardless of the method used to transfer to the card as the original files were transferred using an SD adapter and card reader, and the file that triggered this issue was transferred using the usb cable.

I appreciate any insight or opinions.

Tim