Odometer problem

[mcrucesp]

Hi guys, i have a vw polo 1.6 (gasoline, not diesel) 2004 (9n) and i have a problem with the trip odometer. the first thing i notice was that the button to reset the trip doesnt work anymore (it doesnt reset the trip, but still work for set the clocks time), then i notice that after travel a few kilometers when i turn off the engine the trip went back to zero and today i notice that this automatic reset happen when i was stopped in a red traffic light with the engine on (not only when i turn off the engine).

does anyone know whats couse the problem?

Thanks for your help