Make sure you have at LEAST one backup version, that you update for every good compile. I just had ALL of my brush entities deleted, and it won't resave them in. I'm restarting the computer, but if I can't fix it I'll have to remake map. It just randomly deleted all of it. Kinda like how skybox spasses the fuck out sometimes and doesn't work no matter what. Just watch out and make sure you have a good solid version not too far back you can revive from.
