when i look your laptop up i see it come with windows 8, did you install windows 7 yourself? if so this may be a driver issue
have resource monitor running then start CS:S, join WCS, wait for it to crash, use the graphs to determine if there's partiular problems running WCS
when did this problem first occur? do you remember what you did beforehand that might've caused it?
you could try running in safe mode and see if it crashes, then it might be another problem on your computer closing it in the background (not to say safe mode is a guarentee it won't run, some have been able to bypass and run in safe mode, but the vast majority won't)
it doesn't sound like a crash so much as a program is just forcing CS:S to close, there are some advanced ways to see the calls on your computer to what might be closing it, but i haven't messed with those in quite some time, really i'm hoping it's some silly easy thing to overlook and not a major "core abstract Steam/Graphics DLL corrupt deep in some files that you have to just KNOW the problem already to fix it" kind of thing
hate those kinds of things
A programming genius called HEAP
Had trouble in getting to sleep
So he made his lambs troup
through a huge FOR-NEXT loop
FOR 1 TO 10000: NEXT sheep.