I also share this problem, and it is well documented on this board.
I have not yet finished BG2, I got a little bored of my Ranger, and restarted with a fighter/Mage. I have got to the underdark, and have just about finished that, and I haven't played now in about a month.
I am hoping that my problem is something like my aussie mate Bruce's, in that I simply have to find the perfect class.
Antonius, Your problem seems
very serious mate, I would prescribe 10 hours of playing, in which you are not allowed to change character or restart, no matter how much you want to. If you find that this does not work, try another 10 hours, and you should have settled in with a character in now time!
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"Watch your back"