There's Strange things happening in my home?

Ever since we moved into our new house in October of 2010, weird things have been happening. All together there's 7 of us and two pets. we've had footsteps running/etc up and down the halls, in our rooms and up and down the stairs, we've also heard voices in out attic which is unaccessible and sometimes when we'll be in the middle of a conversation someone starts yelling or once in a while screaming. Doors open and close, mostly the small closet door by my bedroom at the end of the hall. I used to see someone in my bedroom window staring back at me before i finally threw a blanket over it (a very dark and disfigured face, piercing gold eyes). Once in a while it would feel like someone is crawling over top of me and i would wake up in a state of panic from either being awake and feeling it or feeling memories come back again. My dog will growl at something randomly or my cat will stare and follow something with his eyes on the ceiling. It stopped for a month or so and then tonight (May 1, 2011) our disarmed alarm system suddenly went off! Fire alarm, burgalur alarm, etc. and when we checked it it said back door, front door, all the rooms, and the basement were breached or whatever you call it! My entire family, mostly my mom and 4 younger sisters, are freaking out! My step-dad is telling us to ignore it and we keep saying what in the name of cheese would've set it off. I started asking if maybe that stuff was starting up again and he had said no, it doesn't exist nor do they cause things like this. Please! I need someone to help me protective my mom, dad, and sisters!