Gearbox Trouble

My stewardship of the GT-R might be coming to an end. While reversing it in the garage this past Wednesday, the car just stopped. The engine was still running, and it could go forwards, but reverse just wouldn't go. I stopped the car, waited 45 minutes, and tried it again. This time it all went smoothly. Luckily I'm taking it to be serviced this Saturday, but repairs possibly costing up to five figures, I'm thinking about selling it. At least I've had my fun.