04 rancher sift problem

I know there are plenty of these threads out there already, but my problem is a little different. I can start the machine and run it for about 20 minutes to a half hour, and it shifts fine. Then it'll just all of a sudden decide to do the flashing number and stuck in gear thing. I can shut the machine off to try to reset it, manualy shift it into neutral to try to reset it, and it wont work. If the machine sits for half hour to an hour, it'll start up and work fine. Anyone have any ideas?

Start with simple stuff load test the battery to make sure its good. ( the computer hates low voltage) then wiring harness plugs at the computer module that controls the shifting mine was not tight it would up shift up not down. If not that check the shaft sensor / and connector by the driveshaft it tells the computer when to shift and controls the odometer. Mine would not tell me how fast I was going. Hope this helps.