Hi

I am having some problems when playing games on my Laptop.
Sometimes while playing my whole computer will freeze up and just play a high pitched skipping sound.
Sometimes it is 2 mins into a game sometimes it is 2 hours into a game. 

One time it did freeze up but then 30 seconds later unfroze and was fine, but usually I have to hard shutdown and restart.

It isn't all games though, I play a lot of indie games and it never seems to happen with them.
Happens very often while playing COD 5, happens sometimes but not often when playing Tropico 4.

Has never happened when not playing games even when I have pushed RAM to the limit which would point to a graphic card problem to me.

I have updated drivers and got the latest drivers only realesed yesterday and installed them and it is still happening.

My Video card is a GeForce GT 540M inside a dell XPS 15.

Any ideas what I should do to fine my problem (also I have 7 days left on my warranty if this is a hardware issue).