Do you have all the songs in one folder or are they nested in different folders? The CPU in the HU will struggle if you have loads of tracks in the same folder.

Also have you checked if there are any new MDI firmware updates on the mygti website?

That said I'm still struggling to imagine how you have more than 64GB of music that you need to have on one disk (I would just label and swap USB sticks if it came to that, as I'm sure I could split them up by age or genre). To think that once upon a time we could hold around 15-20 songs on a cassette tape or CD