Freak me out

I was just on MSN and some weird person started talking to me, I thought it was a CK person as I have had a few CKer's add me in the past, but this was some guy. I told him because I didn't know him that I wasn't going to talk to him so he got all nasty...it has totally freaked me out. I have used MSN for so long and never had this happen to me, I have blocked him and am curious if this new secret web life is making me paranoid, I never freak out about anything!