Gmod on CrossOver Issues

Hi, I was running Gmod through crossover through CrossOver for the first time and everything was great (except the thrusters lagged everything up) until I headed towards the lake in gm_construct to find that the walls dissappear and sometime a white thing half covers my screen and the lake was all messed up.
Then, I got the same problem while playing Onslaught so I couldn't see the enemy and even WORSE there's these red "Error" things all over the place! I already put all the settings to the max, which didn't solve the problem and lagged everything up. I have the Black MacBook. Here's some pictures:
http://picasaweb.google.com/adodorito/GmodProblems?pli=1
Please help I really want to play gmod correctly!