Scary dreams, do they mean anything?

I've been having some weird weird dreams over the past week. At first I thought nothing of it, but now its been a week, and nearly every night the same guy is in my dream. That person is my dad. I won't go into details about my dad and I, but keeping it simple - I hate him, and we haven't spoken nor seen each other for a year and a half now (since December 2006).

He was a violent loon to put it nicely. The type of guy always out looking for trouble, or starting unnecessary trouble and violence. I admit, at the time when I was 15 I was scared of him, I was scared shitless at the thoughts of what he was going to do, or what trouble he would get us into whenever I saw him. However, its been a whole year and a half now and nothing, no thoughts, dreams, nothing have occurred about him. He is completely out of my life.

So, the dreams. Well. They all have my dad in it. They are all a kind of nightmares too. The first dream (about a week ago) took place in my college. There is a kitchen there and the huge windows have the open view of the car park. On a Monday I am usually in this kitchen until 8-9pm at night with my college class, so the car park is empty at around 6ish. Its day light in my dream, and can't be pitch black yet, but I remember just turning around and seeing my dad just stood there, in the middle of the car park, looking right into my eyes. He had no expression on his face at all, just a blank and numb look as he stared directly at me. I screamed, and woke up in a sweat, the end of it you might think? Nope, think again. I fell back to sleep shortly after and I vividly remember the dream because it continued. I looked back around and he was gone from the car park.. only this time I looked across the kitchen and his entire face was in the window of the door, looking right at me.. expressionless once again.. just starring at me! I grabbed a knife and lunged for the door and he was gone! I sorta just stood there, knife in hand with my friends going "Joe, are you alright.. put the knife down whats going on?" and I was replying "oh my god he was there at the window and in the car park!!!!"...

That was the end of the first dream but I've been having 1 per night now and they all involve the same thing - my dad, staring at me, while I do various things. The scariest was the other night when I was on the tube in London. I was in a tunnel and the lights blacked out for a moment ..there was a tiny bit of emergency lighting on, but in my reflection of the door my dad was standing behind me! His face exactly the same.. just motionless and dead looking. Another night before that I was with a group of friends, I was at the Bournemouth Aquarium, walking through a tunnel with water all around me. On the other side of the water there was another area where people were, and there, staring at me, was my dad, only this time all my friends saw it and were equally freaked.
Its got to the point now where every dream I have, I just expect to see him, and its really freaking me out now!

Last night, it happened again. In my dream I opened my blind and window in the middle of the night to get some fresh air. Standing in the middle of my road right outside my house looking right at me was my dad. Expressionless, emotionless, just looking at me.. I screamed before waking up.

What does this mean? Does it mean anything at all?