ok, I bsp my map and halfway, it stops and gives me this:

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************ ERROR ************
MAX_MAP_VISIBILITY exceeded
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can anyone help me?

Sounds to me like you made it too big.

If it's big and simple then you can fix it by simply adding a key of _blocksize and a value of 4096 4096 4096 to the worldspawn.

If it's complex and you haven't made any brushes detail - if you don't know what that means then you certainly need to do it. You need a tutorial which I'm currently trying to find the link for; lost the blasted thing again.

Ah, found it http://www.nibsworld.com/rtcw/tutorial_detail_and_hint_brushes_part1.shtml)