Possible Duplicate:
Disable Mac startup sound
I tried to disable startup sound by pressing mute button during boot. Then I tried also StartupSound.prefPane application mentioned on several sites (http://www5e.biglobe.ne.jp/~arcana/software.en.html) but nothing works for me. The startup sound is always there without any change.
My iMac is new... bought in October 2010 and of course powered by Intel.