Optio S5n movie audio whine

Hello,

I just bought this thing and I'm dissappointed with the terrible whine in the video clips. I didn't expect pro quality audio but it's really irritating. I haven't measured the exact pitch, but it's about 4-8 kHz and sometimes very loud and sometimes not that bad, usually bad. I don't think it's mechanical because the camera is almost noiseless. Are you familiar with this and do you know if there is any solution. I tried another camera at the store and it was just the same. I like the camera otherwise so I wouldn't want to take it back.

Kiril