Mod_LoadBrushModel:[...].bsp has wrong version number ([...] should be 30).
Really need to see the compile log to answer this. There is almost certainly a compiler error or a bad warning.
But in case not...
Here are a few of the problems that popped up under this situation:
1. You may have errors in your compile, if not then,
2. Your pak0pak.pak file may be corrupted?
3. Maybe the wrong game version?
4. Wrong WC/Hammer version? Earlier versions of WC were particularly prone to this. Use WC 3.3 or Hammer!
5. Maybe another compile will make it go away, or not? And make sure you have the most up-to-date version of zoner's compiling tools....
6. You may have a bad model - like one from another mod or game, or you once installed a custom one? Or you may have a corrupted sprite or model?
7. Have you installed a patch recently? It might be bad....