Ever try to decompile a map, only to end up with the line "map is protected, cannot decompile", or vmex will just freeze? Well, the secret is revealed my friends. Here is one sure fire way to guard your map from those pesky decompiling programs (mainly vmex)
First off, download this prefab:
http://twhl.co.za/mapvault_map.php?id=4128
EDIT: Link is fixed and hosted here
Now, place said prefab here in this directory in your Steam folder:
sourcesdk/bin/Prefabs HL2/Prefabs
Now, open hammer. place the prefab somewhere in the map (anywhere, just make it out of sight) and compile. (it looks like a 3D letter "T" thats orange)
Remember, do NOT rotate, or even translate the object. Use the entity tool to place it accurately on the grid, then go to "Create Prefab".
Now, try to decompile the .BSP. You will find that it does not work! Thats it Your map idea/custom content is savely nuzzled inside the .BSP