Constantly kicked from private servers...Why?

Okay, on the different private servers I've played, that use any version of KOCP, I keep getting disconnected, for "hacking". My anti-virus is off, I'm not running any 3rd party programs, and I've installed everything correctly.

I'm running Windows Vista32. The offical kal servers run fine. Is this a problem with KOCP and Vista32, or maybe the windows firewall? I've even tried with the firewall off though.

If someone knows how I can fix this problem, please let me know, as it is very annoying >.< I find that I get kicked more often in towns and especially dungeons. Rarely do I get kicked out in the fields. This is what makes me kind of confused as to why I get kicked....I don't know enough of the game mechanics to know why it would be different in these areas :S

Thank you for any help in advance :)

EDIT: Oh, maybe this is important too...it is at least irritating. On private servers, my screen will occassionally flicker, and it will say something along the lines of: "Video driver R3000 has failed and recovered successfully", sometimes the flicker really is only a millisecond, sometimes it is 5-10 seconds though.

EDIT2: Mmm...I did search the forums...I found one person that had a somewhat similiar problem, but all that was said by people, was just that Vista is crap, and dual boot or remove it completely....Please don't tell me this ^^; I know this, but I'm unable to do so at the moment with this laptop. Perhaps next summer I will buy a new computer, but that is too far away for me :S