Continuing NOISE in macbook pro??!!!

Just came back to London from Hong Kong this morning. My macbook pro was perfectly fine before the trip.
However when I start the machine when I came back, there is a loud continously noise on the left handside of the mousepad. 'hardrive' maybe??

Please help....this is driving me crazy...

Thanks

Well, as far as I know the Hard Drive is on the left side of the Trackpad toward the front. Is that where the noise is? What does it sound like? Was the MBP with you on the plane or in the baggage? Just wondering if it was not with you and maybe dropped or banged.

Yes, thats where the sound is coming from. Its just sounds like its movin continiously with sudden sounds comin out...however it'll get less when i work on the MBP. e.g. moving the scrolling bar in safari. When I'm not movin the bar or anthing else, the sound will get louder again.

It was with me on the plane, without any knocks or fall...

Really need help!

Thanks

I just plugged in the powersource, the noise is gone. However when I disconnect it, the noise appears again?

Any ideas of what is wrong?

Thanks