my mac is sick

I'm getting long start ups and crashes at the least provocation lately, the only diagnostic hint I get is a hardware error code: 4mot/1/40000002:HDD0.

Does this mean anything to you?
Appreciate any clue as to my next move. I've done everything short of reformatting - it won't partition either: "hd drive won't unmount"

thanks

Thanks guys.
So it needs open back surgery. . .

I didn't search very far 'cause more than a few clicks here and there and it freezes up on me.