Generally I find that when someone starts out with, 'I don't have a problem with...', they really do have a problem with...
You see, you have a problem with guys that are obviously gay. You don't mind guys that are like me, they just blend in with the crowd, but guys that are a bit swishy, or who lisp, or are limp-wristed and f@ggy, well, you just can't stand them at all. They make you feel insecure, they make you feel as though people will look at you if you are around them.
It is this that proves you really do have a problem with homosexuals otherwise you would be happy to be seen with any homosexual, not just the 'straight-acting' ones.
Edit...
You say it is not their sexuality, it is the way they act. How do you think you would feel if the straight acting ones started making out in front of you? Do you think that would make you feel uncomfortable?
Do you think that all of a sudden the gay guys that you are comfortable being around make you feel uncomfortable just because of their actions? You say it isn't their sexuality that makes you uncomfortable, only their actions, but it is the actions that are overtly homosexual that make you feel uncomfortable.