if you don't have the "For Apple" chop + guarantee, make sure you save your work, before allowing your Mac to sleep.
Any crash / hang would probably be caused by the non-Apple RAM.

um... very few apps support more than 4 GB. what apps are you using now?

Xirality : if you can't understand what he's talking about, why are you listening to him?

you can use ANY RAM that matches your spec. the risk with non-certified RAM is that in sleep mode (when you close the lid of a portable Mac) ... you might suffer a system hang / crash. my suggestion is simply save everything before shutting the lid. so even if it crashes, you'll lose no data.

if that is not an acceptable risk for you, then go ahead n buy the certified RAM.