On some intermittent problem, that I have had in the electrical industry and other places, I have often resorted to unplug everything and plug it back in and it surprises me how often this grenade approach works, covers more area than a shot gun approach . My theory is that one pin some where is making and breaking contact, whether dirty, corroded, not seated properly, etc. gets a better contact with this procedure, And I assure you, it has worked for me more than just a few times. I would start with the plugs at the computer and eyeball all the pins in the plugs to see if they all protrude the same amount.
Hang in there and if you don't get it fixed, remind us periodically and maybe someone will have a good tip for you.