I need my space

So I have realized after living with 42 different people since high school that I have space issues. I have certain things and places that I do not like to share with my roomates, at least the roomates who get on my nerves. I think that living in close proximity with certain people gets on my nerves. I find that I'm less willing to let them do things like use my computer or watch tv in my bedroom. I told my new roomates they could watch tv in my room anytime but that was a mistake. The roomate got on my nerves a lot before he even moved in. I put a password on my computer before he moved in because I didn't want him screwing with things, but now I'm going to have to take back what I said about the tv thing because I need my space.

So what do you think about space? Have you had any space issues with roomates or spouses or anybody in particular that you've ever lived with? Please share them so I'll feel like less of a jerk.