Transfer case popping into neutral while driving

[Douga]

I'm wonder if anyone could lead me in the right direction as to why my transfer case or four wheel drive shifter pops in a neutral when I'm driving down the road and when I'm backing up I have to put it in for high otherwise it just pops out and then it locks up to Wheels when I'm going to reverse and for high if I turn the steering wheel. Anybody have this kind of issue mine is a 98 Dodge ram four-wheel drive 5-speed manual transmission with a 5.2 Magnum in it .