My computer sometimes gives off an hysterical laugh, which is somewhat unnerving. What can I do?

BTW - I believe that the sound system is somehow involved (whether hardware, software, or both I don't know).

My reason is simple - the sound on my Powerbook 'sleeps' after a period of inactivity, and the 'buzz' goes away ... 'wake' the sound (usu. with a system event), and the buzz returns.

Now, I consider the 'sleeping sound' to be a B-U-G, and have search high and low for info about it ... but, bug or no, it does illustrate something interesting about the buzz.

You've hit a common complaint .. I suffer with it, and so do many others:

Apple Discussions - purring Ti book . . . !
http://discussions.info.apple.com/WebX?13@@.3bb97c21/83

... and even on Slashdot ...

Why Does a Screen Re-Draw Make Noises?
http://ask.slashdot.org/askslashdot/03/02/...41254.shtml?tid=137

I also just noticed that when I have a blinking caret in a text box (like the one I'm typing in now) I get a little click sound from the computer with each blink. Is this what you're experiencing?

I definitely get a weird soft raspy buzz noise when I move my mouse pointer, especially when I'm dragging windows. Sometimes it happens when gifs are animating on screen too, which led me to believe it was disk related somehow.

I get something very similar on my PowerBook (only 2 months old). It's not related to any physical activity (like typing, etc.) -- at first I thought it was a clock ticking -- it is _very_ regular but somewhat more than a second between "ticks" -- it sounds much like the hard drive sync'ing, although that doesn't seem to be what it is. Your explaination sounds logical (I don't think I've noticed it in battery-only mode either... will check that!).

Interest to hear any solutions!

I get the same thing, but it was well before 10.2.4. It started when my TiBook was about 9 months old. It seems to come and go, but I've never had it freeze any applications. My TiBook is about a year old now and it doesn't do it very often anymore. I still have no clue what causes the noise though.

Ever since 10.2.4, I got a high pitch soft whistle too often with my 15" TiBook. Mail.app, if open when I put the computer to sleep, always freezes after waking -- with that high whistle humming in the background. Clicks or keystrokes *halt* the whistle, or interrupt it for a flicker -- but then it's back on again, as soon as you release.

Force Quitting Mail stops the noise. I had heard the noise before -- notably with Help as of 10.2.0, but this is the most consistent it's been. Other apps function fine when Mail is crashed and whistling.