Have you tried changing out the battery or cable? My tablet seems fine so far, and it was from one of the very first batches. It (very rarely) will 'die' out for a few milliseconds and causes me to mess up in a song. It isn't enough to make me super mad, and I'm pretty sure it's due to my cable being a bit faulty. I'm also thinking it might be the battery in the pen maybe somehow jiggling out of place momentarily.
I'd suggest trying a different cable first, though. The first cable I had, that came with the tablet, would give the tablet power only if it was in a certain position, then would disconnect if I tried doing anything. I snipped the cable and cut out which part I thought was bad (I jiggled my wire a lot and saw that if I jiggled this certain section it would disconnect/connect) and taped the wires inside back together and it worked perfectly fine (though it would disconnect if any of the wires touched each other. Understandable). Of course this was only a temporary fix until I got a replacement cable.
I'd suggest trying a different cable first, though. The first cable I had, that came with the tablet, would give the tablet power only if it was in a certain position, then would disconnect if I tried doing anything. I snipped the cable and cut out which part I thought was bad (I jiggled my wire a lot and saw that if I jiggled this certain section it would disconnect/connect) and taped the wires inside back together and it worked perfectly fine (though it would disconnect if any of the wires touched each other. Understandable). Of course this was only a temporary fix until I got a replacement cable.