I bought one last week and had similar problems. My mp3 files are greater than 12MB. When playing these files, my YP-MT6 would reset any time I tried to switch to a different file or even if I tried to turn it off (had to pull the battery out). It did the same thing with equally large wma files.
Here's the fix: return for refund. I did that today.
I've just bought a Samsung yp-mt6 and was very impressed with it until I ran into this problem: I record mostly classical music, and the first of several movements of one piece in mp3 format is slightly over 9mb in size. Whenever I try to get the player to play that track, it shuts down automatically and restarts. Another track of 6mb, however, will play. So I wonder if anyone has run into this problem, knows the cause, and possibly a solution?
Thanks!

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