Macbook Pro internal speakers cut bass off when I increase volume

Hi I live in Athens, Greece. I've bought a new macbook pro about 3 months ago (bought it in New York) but have a problem which just started out of the blue! Everytime i play music (using the built-in speakers) the bass just cuts off (!). When i tap (not too hard) the surface to the right of the trackpad, the bass momentarily returns for a second or two, and then just goes away again (when i tap it on the left of the trackpad nothing fixes at all).
It seems like its a hardware problem (otherwise it wouldn't fix even for that second when i physically tap it... right?). Is this something that's happened to someone else who might advise me on who to solve this? If it is a hardware screw-up, does anyone know if I can take it to a local Apple dealer and get it fixed on the spot? (There's absolutely NO WAY I'm leaving it there as I have over 200gb of music in there - that's my professional library - and I'm not risking any Greek technician just sticking in a usb hard drive and copying my music library!) And, it's more than just a pain in the neck to have to format it so i can take it to be fixed...
I'm thinking that the speakers probably aren't burnt, because if they were the bass wouldn't come back (even momentarily) when I tap the keyboard would they? Maybe it's just some wire or something falling out of place inside the mac...
Anyone?

Could be a loose connection. Does it do it for one speaker or both? If it's both, then it could be something other than a speaker connection. In any event, you should have it looked at by an authorized Apple dealer in Athens. You can always remove all your music to an external hard drive prior to taking it on in.

Regards.

no - its both speakers. when i said "formatting" it being a pain, i meant having to delete my library from my macbook (once i've copied it first) and having to copy it back to my macbook after it's been fixed.. That's why I'm asking if this is something that happens regularly to macbooks, so that you might tell me what usually is the problem (so that i know whether deleting the data from it will be necessary...)

Any ideas as to what it could be?

I just ran into exactly this issue with my MacBook Pro, though tapping the surface next to the trackpad no longer works to get the bass working again.

nounix, did you find a good way of fixing this problem?