I'm pretty sure that time paradoxes wouldn't happen; if you went back in time to kill your dad, then you'd just be living in an alternate reality where your dad is dead and you don't exist (officially; you'd still, y'know, be there). And in the other reality, things would continue as normal, although you'd have disappeared. So, yeah, time travel can still screw you up, although it wouldn't make a universe-destroying time paradox.