Chevrolet Repair: 2004 silverado, speedometer needle, silverado truck

Question
Yesterday my speedometer stopped working correctly on my 2004 silverado truck.  I have drove the truck twice since the speedometer stopped working.  What is happening now is when I start the truck the speedometer needle is on 100mph and as my speed increases the needle moves forward like it is working, only it is off the chart.  When I stop at a stop sign the needle comes back to 100 mph.  All the other gauges on the control panel cluster is working fine.  So it does not seem like it should be a bad fuse.  I have not added any new electrical systems.  Is there a way to get it back to 0?  Someone suggested that it may be a stepper motor failure.  

Answer
yes, you need to replace the instrument panel, then you have to have a gm tech reprogram it. there is a technical service bulliten on that. if your truck is still under warranty, it will be covered. if not, you have to pay for it. sorry for the bad news if no warranty.