MacBook Pro odd sound issue

Whenever there are 2 sounds that are played at the same time... for example, I have a song in iTunes playing, then I drag something in the trash,
The volume for the song in iTunes gets really loud for the duration of the other sound playing.. If that maks any sense.
It does the same thing when I have a song playing, and I drag something out of the trash, or move a file.

Another example... song playing in iTunes, then I press the volume up button, the sound gets really Loud for a split second.

I don't know, its hard to explain. Its something I can live with, but its just one of those annoying things that never happened with any of my previous Macs. Especially anoying if I'm moving a lot of files around while I've got music going.

This happen to anyone else?

Edit: Using a 17" MBP C2D... Tiger 10.4.10

Bump-
Would someone be willing to try one of the above described, and see if their system does the same thing?

i tried both - dragging item to the trash and rising volume - on my MBP everything is OK

Did you try it while having a song playing in iTunes?