runs for about 5 seconds?

Have you ever cleaned the inside of your treadmill. If you have
never cleaned the inside you may have a dirty speed sensor.
Clean that first.
I have a video on this to show you how.
"Maintaining Your Home Treadmill Revised"
http://www.mindbites.com/person/214-Mark
you can also e-mail me if this doesn't work
markepeterson@austin.rr.com

I'm suprised you didn't get an error code

Mark Peterson
March 2008