Odd Speedometer Problem

Greetings and Salutations... I recently acquired a 1999 F-350, Powerstroke, with about 99,000 miles on it. The truck is in really good shape except for a couple of minor problems. First off, the driver's side backup light appears to NOT be getting power. I have not poked about to find out if it is a fuse problem, or a wire problem. however, that is not the real "problem"...just mentioning it for completeness. The odd thing is that in the past couple of weeks, there have been four times times that I have fired up the truck, and, everything has worked except the speedometer. The needle has stayed dead and the odometer has not moved. The First time it happened, I thought "oh no...expensive replacement...and a pain while it is out". Then...I discovered that if I turn the truck off and back on, the speedometer wakes up as normal! I have poked about on thedieselstop and a few other places, but other than some indications that it might be a sensor going bad, have found no similar problems mentioned. While I could be wrong, it seems to me that if it were a sensor dying, it would not wake up when I restart the truck... I have not tried getting the codes read yet, although I suspect I should, just to see if the computer has anything useful to say... In any case, just throught I would post here to see if anyone ELSE has run into this problem. Regards Dave Mundt