Funny thing is when i saw this error i know i had seen it before but when i did a search i couldnt find it either.
Lucky for you I am a resourceful and stubborn lil bugger and found this answer for you:
Max points on winding means you have more than 64 vertices on exactly the same plane. If you have a ladder that long, you are wasting a lot of face count. Each rung has at least 8 visible faces. You may want to reduce the number of rungs, or use a transparent ladder texture for the rungs. There are a number of them in the common folder.
This was posted by a genius guru named Balr14 almost one year ago. Funny like an anniversary question.
After looking at your pic [Very Nice Lookin BTW!!] i see what you need to do is possibly replace the arches somehow. Not an easy task i know but nessicary non the less.
I do what you say, i replace the 60 arches whit a custom texture, but after compiling i have the same problem.
What can i do now? Maybe deleting all the battlements (60 brushes) it runs, but these are necessary and i cant remplace them whit a texture. They should be 3D work, not a plane texture.
Ah.....of course. The errors are different, but are similar in nature.
The error you have is because all those battlements are along the same plane, not because they are contacting a brush. Try staggering the thickness of the battlements. Push some forward, and pull some back. That should solve the problem.