Crash in materials menu

Hello.
Now and then, Garry’s mod crashes while I am using the materials menu. It crashes on one material, on second run it does again. After deleting cache it is again working well, but it is very annoying when you build something and then you are just going to make it looking good and your game crashes.

Crash dump: http://dumps.garrysmod.com/?view=2623524306

Thanks.

Do you happen to be using a mac?
EDIT:
I was being retarded since i hadnt looked at the dump :L
So I dunno.