Macbook won't wake up

My Black MacBook is on (I can hear it whirring) but there's nothing on the screen nor will it make any noise (when changing the volume, for example). And when I close it, the sleep light comes on but it doesn't start 'breathing' and the computer continues to whirr as if it's still on.

What's the problem?

Am I right in thinking I'd lose my work if I do that? From what you're saying are you suggesting it's crashed?? That's not an option. I thought Macs can't crash?

no external monitor. So it seems it's crashed. Brilliant. So much for "They just work" - seems they're just as bad as Windows then.

Rubbish.

In fact my Mac is always having problems (never to this degree but its forever dropping wifi or not connecting at all, the other day it was really hot because finder was using 100% of the CPU for no apparent reason, the spacebar stopped working a few weeks after buying it and I had to have the battery replaced within the first six months to name a few problems).

My Vaio with Windows 7 (which I'm on now) is incredibly stable and, apart from a couple of minor program crashes, I've had no issues. And never lost any work.

For me, I think this is the last nail in Apple's coffin.

Thanks for your help though. And apologies for the rant!