Kinetic Energy isn't a conserved quantity, energy is (barring time zero of course) and so is momentum, but not kinetic energy. Entropy is a non-conserved quantity too, barring time zero again. Though in any steady-state model entropy over an infinite period of time does go down occassionaly. Again, in a steady-state, because if you take a deck of cards in an order and shuffle it, it's entropy will increase, but if you shuffle it enough times, it will return to it's orginal state. This principle leads a lot of us to believe, and God I hate this term, that the 'multi-verse' may be a steady state system. Even there though, you do end up back at the 'where the f did it originally come from' issue.

Lot's of people play with a 'temporary quantum flux' thing as the origin reason, since energy only has to be conserved over a specific ratio of time to energy and that time is governed by the fundamental constants, which might not be the same outside our 'universe', but then you still fall into the 'so where'd that other stuff come from' issue. But it might explain our universe's origins, under the 'over an infinite period of time it shall rain snickers bars' rule of quantum mechanics.