Is getting ANNOYING. I’ve detailed a load of crap, and still can’t find it. I haven’t added many complex things to my map, but I have added a LOT of things to it, and I’ve been trying for hours to find what leaf it is that’s causing this error on -vis. Can someone give me some help as to find which it is? Maybe look for me, or tell me a link as to how to find it?
Thanks.
http://www.wemakemaps.com/hintbrushes.htm
http://www.surfacegroup.org/tutorials/hint_brushes/
http://www.katsbits.com/tutorials/idtech/q3map2-error-messages.php?subaction=showfull&id=1135215997&archive=&start_from=&ucat=15&
I suppose understanding the concept better, should give you the power to find the problem 
…
also first link has some hints on how to place hints…
I guess you know that, anyhow:
quote from http://forums.urbanterror.info/topic/10214-common-error-messages/
Leaf has too many portals
This error is results when one of the leaf-nodes in your map meets too many other leaf-nodes, and therefore has too many portals. To fix it you can split the offending leaf-node up, or reduce the number of leaf-node it meets.
To reduce the number of splits made you can simplify the brushes in the map. You can also make the compiler ignore certain brushes by tagging them as “detail” (Ctrl+M with selected brushes).
To force a split in the map, you can use a Hint brush, which is an invisible nonsolid brush which only q3map can see and use (Hint brush = axial brush with all faces common/hint). (Courtesy SmallPileofGibs) (QER)
Well I narrowed it down by selecting a huge portion of my map, making it detail, saving and compiling under a different name. Worked. Went back to old map, made it a smaller portion, worked. Went back to old map, made it a smaller potion until I found the exact thing 
leaf with to many portals happens when you have very small details that you forgot to set to detail brush.