H6 Freezing during playback

[tooday]

I recently purchased a refurbished H6. The recorder will sometimes lockup/freeze when I play all the recordings in folder 1 (I have about 30 one minute recordings). I have used different sd cards, did a factory reset etc.. I am wondering is this is just a problem with the H6 in general or is it specific to the refurbished units. This is actually my second refurbished H6 - I returned the first one because it would lockup/freeze a lot. Has anyone else had this problem?