Comment 47 for bug 199088

I'm also affected by the annoying sound thing.

For me it only occurs when multiple users are logged in and it seems to be the gpm instance of the inactive user that makes the noise.
This can be verified by disabled sound in System->Preferences->Power Management->General for the other user and suspending using the suspend key on my laptop.

Sometimes I don't hear any sound when suspending. Instead, after waking up the computer and after switching to the inactive user, the computer immediately suspends again (without me taking any action).

My conclusion: Probably some race condition when multiple users are logged in (and multiple gpm instances are running).