Turns on fine, then goes to the sat. page and starts tracking sats fine. i can scroll through pages fine, everything seems normal. but after about 30-60 seconds or so the unit "locks up" and the screen only displays a vertical line. i have to take the batteries out to get it to reset itself, but it does the same thing every time. a weird thing is, the vertical line is in a different place each time but its always a vertical line. this happens even with fresh, meter tested (1.62v) batteries any ideas?