Hey guys,

I was about to open my map and suddenly radiant gave me  an error: FATAL ERROR: Unhandled exception caught GetLastError()=0 An unrecoverable error has occurred. Would you like to edit Preferences befor exiting Q3Radiant?

I have to add, that I had a few problems with the skybox which I tried to add to the map. But I couldnt compile the map.
I have another map which one works fine.

You probably spelled the skybox kvps wrong.
Make a backup because it can erase your map if you keep trying to open it with a corrupt worldspawn.
Open map_source/broken.map and open your working.map in notepad++ and compare the worldspawn section at the very top.

Thanks. I solved it in another way: I deleted every brush of the skybox in the map. I tried to add a new but its bugging. Everytime I set it up, the textures are bugging.