Thank you very much to all of the = people who replied to me so quickly,
but it looks like I've got the problem licked.  I went out and looked at the
battery connections like = Stephen suggested, and, sure enough, the battery
connections were loose on = both sides.  I guess the vibration just loosened
them over = time.  I dabbed some dielectric grease on the terminals, snugged
the bolts = back up, and everything looks good.  If I experience any = further
problems, I'll be asking for more help, but the connections were pretty
sloppy, so I = suspect that's the root of it.
Thanks again!
-Jason Stevenson