When does Paranoia become overkill?

Okay its quite alright for you to be paranoid. I do believe it keeps you on your P's and Q's... However, does the constant saftey measures and security features(on the most minimal objects and tasks) cause you to beleive that everyone is after you, ever make you wonder what kind of acts you may have committed in a past life? Or for that matter, the acts you have committed in this life. If this is the kind of person you are do you ever get the feeling that the people around you really dont know who you are? Why do you think every cop is after you...even the ones on the otherside of the highway. At what point does paranoia become overkill...the results of which make you live a life where the fun is sucked completely from it.