Team Fortress 2 crashes when i join an online game an error screen comes up saying "hl2_osx quit unexpectedly." Does anyone know why?

The game opens no problem, but after 1 or 2 minutes of gameplay, the game crashes, the screen returns to the desktop and an error message pops up saying "hl2_osx quit unexpectedly." and under it, not in bold letters, "click Reopen to open the application again. Click Report to see more detailed information and send a report to Apple.

Ive been all over google reading articles to try to resolve this but I cannot figure it out, if anyone has any ideas, please let me know ASAP.

Thanks