79 Mph!?

This is my bike computer. It tells me things like current speed, max speed for this ride, distance travelled, etc. It's currently showing what it thinks was the maximum speed for my ride on Wednesday, April 17th, 2008.

I can't explain this.

I know I went down some hills very fast, but I'm pretty sure I never hit 79 mph. Probably 50 or a little higher, but not 79.

Still, computers are never wrong...