Mac Book Crashing/Restarting

I am having a serious problem with my macbook crashing and restarting. I have a unibody macbook 2.4 Ghz Intel Core 2 Duo, 4 GB memory. There are a couple of things that it does,

1) Crashes, screen active, but no input through keyboard or touchpad
2) Crashes and restarts.

Sometimes this generates an error message to send to apple and sometimes it does not.

It seems to happen when either the USB is moving a lot of information (above say 2-3 GB or when I am watching a DVD. It seems to happen when the computer is working harder. This is happening a couple of times a day. It is still under warranty. This seems rediculous for such an expensive machine. Any thoughts would be greatly appreciated.

What does the crash report say? Even a non-tech type like me can often spot a clue as to what's happening by reading the report.

I will have to take a look next time it crashes, unless someone can tell me how to find the history of the logs. I have glanced at them, and nothing stood out to me.

So it looks like the last several crashes involve VLC and WebKitPlugInHost. The reports are long and very difficult to understand.

Are others having this problem. Does it sound like hardware or software? Gremlins?

Thanks in advance for your thoughts.

got some issues as well like these and some other people as well complaining about crashes & macbook turning slow.... start to think its the memory... i bought mine june 2009, macbook aluminium as well, same specs, only 2Gb ram... i noticed in widgets on isat pro, when i add up the numbers there, i never get to 2Gb, while with my previous white macbook, it was 2Gb when i added them up... can u check this? when did u bought it?