Q. What is this "Bad Surface Extents ????/0" error?
A. This is most commonly caused by having a really large brush. Sometimes a brush doesn't necessarily have to be too large, but if the texture is scaled down too small on it, you can still get this error.

The way compiling works is that on a standard texture scale (1.0) the compiler will break that texture up according to it's scale. In the case of 1.0, it doesn't have to. However, when you scale down the compiler has to make more cuts. The lower smaller the texture becomes, the more the compiloer has to cut. If it has to cut an insane amount of times, you can get this error.

On the flip side, scaling too large can give you this error as well. The solution? Find the offending brush and cut it into two or three smaller pieces using the clip tool. This will generally solve around 95% of the problems associated with this error. However, in some cases, this error can also be generated when you have an invalid shape. These generate floating point values that cause problems during compile. You may not know what that means, but WorldCraft usually does. Go into WorldCraft/Hammer and click on map > Check for Problems. This will point you to the offending brush and either fix it for you, or allow you to delete or fix the brush yourself.