Tlax is right, Thanks for another great Error Link. The best one I know of is http://www.slackiller.com/tommy14/errors.htm
Another place to look for errors of this kind is the help file contained in ZHLT original file, that came with ZHLT 253 before the custom builds.
Here is what ZHLT say's:

brush 'outside world'
Example:
Entity 10, Brush 0: outside world(+/-4096): (9000, -64, 216)(9000,23,283)

There are a few cases that create the 'outside world' error. The first is an damaged brush, almost always created by a vertex manipulation gone wrong. The coordinates listed in the error are very important in diagnosing the error. If any of the coordinates are -9000 or 9000, then the brush is damaged, and most likely needs replacing completely. The second most common case is actually having a brush near or outside the edge of the allowable region for the world. The brushes are expanded slightly for some of the calculations during a compile, so brushes near the edge within 64 units will cause the error too. The cordon tool creates brushes automatically to box in the cordon region, and their brushes can sometimes be quite large, and also extend outside the world. This can be verified by opening up the .map created by an export with cordon enabled, and looking to see what brushes it made.