I was reminded the other day while I was having alternater troubles, that if something isn't grounded, the car will act funny and won't start. There are two metal things, one on each of my battery cables, with some wires that are actually grounds. Check around your engine bay and car to make sure a ground hasn't come loose, and check your alarm for the same thing. If the alarm isn't grounded it might not start.
I could be wrong, but I think that could be your problem.
~Paul
