Screen prompt kvt 617p/na

I am getting a prompt on monitor screen that says that there's a disconnected cable(kvt-617 w/nav). This is the second time I've had a problem with this unit. The first was approx. a month earlier when the screen would shut off when I hit a bump in road and would come back on when I went over a speed bump. I later took the dash apart(2002 escalade) and tried to move the wires around to make sure they were connected. Eventually after poking and prodding for 45 or so minutes it began working again and didn't have any problems for a month. I went out town for the weekend and 2hrs into the trip I stopped to grab a bite got back in the truck, the screen stopped halfway thru it's normal routine with a prompt that said something to the effect that it had detected a diconnected cable. I returned to the audio store where I purchased the unit but they were really no help at all. Any suggestions on what could be causing this? I took the dash apart again and fiddled with the wires to no avail.