This has just begun to happen about 3 days ago, have had my Macbook for ~8months. When I wake my macbook from sleep there is the usual HD boot up sound, but then after that, there is this other sound which I can only describe as sounding like when the trash is emptied, though only lasts half as long. It seems to be coming from the hinge area [below 'MacBook' text] or the screen itself. I thought it may be the speakers, but increasing/ decreasing/ muting the volume has no effect. Just to mention seeing as the screen may be involved, I found 2 stuck pixels [side by side] yesterday but turning off screen then turning back on fixed them. Using: MacBook C2D 2.16GHz; 120GB HD; 1GB RAM; Tiger 10.4.11 thanks, b.