Hi, usually this problem is transmission related but I proved it to myself by driving the car with the boot removed and this never happened. With the shifter in 2nd or 4th, the folds in the boot are all in contact and bunched tightly together, like a rubber spring against the shifter. Because the engine/trans are not mounted rigidly to the body, they move relative to each other. Hit a dip or bump in the road and boing, the shift pops out. This is partially exacerbated by the fit of the console, there is a piece of flat trim which I have enlarged the opening to make clearance for the boot. Seems like a prior owner may have replaced the boot with an aftermarket part because the plate which holds this to the transmission tunnel has screws positioned differently. Don't know the manufacturer. If someone has had this experience and found a replacement boot that is more flexible.