Yeah your map has too many lightmaps for Hammer to handle, which is quite interesting, considering you only have 43 direct lights. Anyway, to fix, click Edit > Select All. Open up the texture browser thingy, put "Lightmap Scale" at a higher value, I tried 32 and it worked, but you can lower it for better lighting detail for releases (I usually use 24 for releases).
Aside from that, the problem would not have been fixed from putting nodraw over everything, nor from func_detail-ing everything. And as John said, you're either mapping off-grid or with a really small grid size and I encourage using a larger one (8, 16, 32, etc), I recommend 16.
I also highly recommend that you don't place anything too close to the edges of the grid (I think about 1000 units off in all 3 axes should be a good rule of thumb), since that can cause errors as well.