Gmod gamemode zombie survival crashing constantly

Hello i have recently boguht the game and 1 of the reasons was because of zombie survival mode. when i first tried it i played for like 5 min then my survivor guy died then RIGHT when he died, it crashed, hl2.exe has stopped working. i thought this was 1 time thing so i tried again played for like 5-10 min then my survivor guy dies and gmod just crashes crashes and gets hl2.exe has stopped working. this has always happend ALWAYS and i really want to play it. please idk why this is crashing but i really want to play it. does anybody know why this happens and how to fix it? this also happens in jailbreak when the last guy of either the prison team or gaurd team dies.

have you got a good computer if not turn graphics down hope it helps =) anyway my opinion zombie survival is crap

yeah i already have the lowest settings set and my com is very good, 2.4Ghz and pixel shader 4.1 ATI radeon and windows 7 home premium

[editline]10th July 2013[/editline]