ps3 freezing…when playing on-line

I’m having a small problem with my ps3. Every now and then it freezes when i’m on line and i try to check my messages (ps3 button)while playing a game It only happened 3 times but when it did i didn’t play it for more than 2hrs at the time of it freezing. I had to hold the power button off. I’m not sure if that will further harm my system by me turning it off like that.

MY ps3 stands vertically and well ventilated.

My ps3 is only 4 mos old. it’s a 80gig I still have the box but i don’t know which set of numbers is the sku #, if that would help at all.

 

If anybody think they might know what is going on plz let me know.