Well... im sure the strain you smoke has a great influence in the effects you get. Sativas are well known to cause anxiety and even pannic attacks in inexperienced users. Yet indicas are very relaxing, calming and are used to treat anxiety. So try to find the best strain for you.
And i know very well what you mean about despersonalization. It feels like you were "outside" you, like if you were controlling your body as if it were a robot, not "you", dont?
Well... while it may be not very nice when you wants to enjoy the high, it surely has a LOT af advantages (at least for me). I love being it this detached state, cause i can always keep my mind cool, without being influenced by anything, as it is "separated" from the body. It was a GREAT help when i was a teacher, cause im VERY shy, but as i was "outside" me, i could relax, cause "i" wasnt there, giving the lectures, i was only someone who was controlling a body at distance, so i hadnt anything to fear... and thus i was able to give excellent lectures, cause my mind was always cool and could think the best thing to say, without any shyness of anything like this. And my pupils just loved me! Also, being in this state allows me to always be a very good person to talk to, because i always know what to say, when to talk and when to listen, because im not involved by the talk, but only controlling my body that is, and so i can have a clearer view... also i can decieve almost anybody, because i can make my body act like if it actually were thinking and feeling what i command it to... also, its a GREAT help whenever i had problems, because i would enter in this state and "step outside" me and view the problems from an outsider view, that is far more unbiased and right, and so i could think about the problems without being too much involved in them, so i could take the best, more rational and cool minded decisions.
So, i think this state can be very useful if you learn how to benefit by it... so good luck and keep smoking! :thumbsup::rastasmoke: