Unable to load some war3 maps

When i try to edit some maps (most of the actually even when it says its unprotected it comes up with this error) Unable to load file 'C:/Warcraft III/Maps/Download/themap.w3x


yet when i play it in multiplayer it works fine


it says it cant load trigger file or sometimes other stuff

ocassionaly it comes up with a critical error and crashes

any help please

The map is protected. You cannot open it with World Editor.
How can you tell whether or not its unprotected? You said it says its unprotected.

Make sure you have the newest version of Warcraft.

If it still doesen't work, it's propably protected.