Rear Windscreen Rattle...

[gsdude]

Whenever I listen to bass music on my stock stereo at around 40% volume or above I get a rattling from the back...after snooping around with the volume up the other day it appears to actually be the rear windscreen itself (or something rattling against it perhaps) that is the culprit, as when I press firmly against the glass from the inside it greatly reduces the rattle to almost nothing.

Anybody else had this problem? And is there a known easy fix?

It's slowly grown worse over the last few weeks and is starting to really get on my tits as I'm a little bit of an audiophile and like my music to sound crisp and clear. I Never had this issue with my last IS which was actually a good few years older than the current one and I used to push the stereo harder when I had that car. Both the same spec IS200 SE with stock soundsystem...