do me a favor, download the ultimate boot disc
http://www.ultimatebootcd.com/, boot up the laptop to memtest.
Those temps aren't actually that high
for a laptop. Besides, a DVD movie shouldn't overheat the graphics chipset that much at all. MPEG video is just not that big a strain on modern graphics. Also, laptops will always read higher on things like speed fan, because they are designed as big giant heatpipes.
Run memtest for at least half an hour. If it comes up with any errors at all, then memory is your problem.
HP consumer laptops really aren't that bad - they use fairly common parts, the same boards in the HP's are in the Dells. However, the MEMORY used in those laptops is ****e.
It is also possible one of the memory slots is bad too. If you have two sticks of ram, pull one and try to make it crash again.
You're real problem is that before you contact warranty (and in the first year, you should just be dealing with HP directly, preferably via Email) you need to have a pretty good idea of exactly what the problem is. This is mostly due to the fact that Customer Service tends to deal with people that screw up their own machines and don't have a real problem, so they suck at diagnostics. If you can narrow down the problem to either memory or the mainboard itself, you can then get them to actually replace the faulty part.
I would go to HP's site and update the graphic drivers and the firmware, and I'd run memory test to rule out the ram. The guys at Frys, Best Buy, etc, do not do diagnostics. They refomat.