95 SL2 Auto Hangs Up In Gear

OK, figure this out! You're driving about 50 mph and all is fine...untill the car drops down to 2nd (?) gear on its own and will not shift back. The only way to get the tranny back to normal is either pull over, shut the car off, start up and go (my wifes solution). I, on the other hand, don't bother to stop. I just shift the auto tranny into "N" turn the car off, and when the engine stops, start up and shift into "D" and all is OK. This situation happens a couple of times a week. Saturn says, replace the tranny. I don't believe them....of course, it would solve the problem. Any ideas?

check the wiring harness on top of the transmission, and repost of saturnfans.com. while you are there, search for "loose input shaft nut"