Check your 5V supply. I had this happen to mine and the 5V supply was weak, sometimes down to <3 volts. But what was really strange was if I swung the cover open on the PS, the 5 volt would come back, then close the cover again and it would slowly drift down. Never did figure out exactly what happened, but it acted like gravity was affecting something, a capacitor maybe?
I finally replaced the 5V supply with a standard computer PS and it worked fine until I upgraded the controls.