Map crashes whille testing *Help!

Ok, its not exactly gmod but…
Im making a l4d map, im just following the tutorial and not really going in depth, just learning the basics, but every time i test it it compiles it, lowers the resolution(enlarges everything), and flashes the screen black for a second like its opening a game, and sits there until i click/minimize the window and it stops responding, i fixed the pointfile, and i dont know what could be wrong, please help

Post a compile log. You may have an invalid brush or a fatal error.

Also, whats the tutorial you’re following?

compile log what? (im a nub, have patience with me)
and im using this tutorial which was linked in the L4D Authorizing Tools

Uncheck run game after compiling. Then load your map by going into the L4D Console (after compiling) then type “map <mapnamehere>” without quotations.

i expected i might ending up having to do that, but thanks it worked