Jumping Speedo Problem

I have an 02 Ram with an automatic transmission and the 4.7L engine. As of up to a couple weeks ago the truck has been flawless. But now, a problem has come up. When I start the truck and just idle it, regardless of what gear it is in (PRND21), the speedometer needle jumps. At first, it only jumped up to like only to like 20 or 30 mph, then today, it jumped up to 120 mph. And the truck is just idling! Also, the ABS light also comes on. Any ideas on what the problem might be. A friend said it could be the VSS, Vehicle Speed Sensor), but I'm not sure. Thanks for any help. Hopefully, the part will be covered. The truck only has 5,000 on it and is covered for 3 years/36,000 miles, but we all know how dealers like to work their warranties. Thanks again.
-Chris

i had the same kind of problem in my old chevy celebrity. all i had to do was change the computer in it. the computer for that old hunk of junk was pretty cheap...but knowing how much parts for all these new car parts...it will prolly be expensive. best bet is to go to the dealer and see what they say about it.