Deadly screech emitting from my Powerbook G4 has skype friends screaming

Hey, this isnt a physical hardware sound. Its a sound i cant hear, but everyone in my skype conference can. I usually can tell when it starts by the shear terror and screams from participants in the skype conference. It doesnt happen every time, but usually every other day or so. I cant figure out what it is, and it started happening without notice. Could this be damage to my mic? Is some terrorist process trying to feed inputs on the microphone line in causing a collision of zeros and ones? If anyone has had this happen to them, or might know why its happening, I could really use your help.

1.5GHz Powerbook G4 12"; Machine Model: Powerbook6,8; Memory 1.25 GB DDR SDRAM

Thank you, although none of your replies really help me.

They are sudden sharp loud screeches. They started happening out of nowhere. To make it stop, i have to hold and un hold. Like i said before, i cant hear the sound, its only being transmitted to the people in the skype conference.

I've since reinstalled OS X and it didnt help. This sucks.

Solution

The sound I was hearing was far from feedback. This is just an update on how I fixed the issue incase anyone else experiences it:

A manual refresh in Skype's data traversal information:
The procedure is as follows:

1. Quit Skype
2. Go to the folder ~/Library/Application Support/Skype/
3. Delete the file "shared.xml"
4. Start Skype

If the above does not help, a reinstallation may also prove to be of assistance.

* Close Skype
* Open your Applications folder and drag your copy of Skype to the trash.
* Search for the keyword "Skype". Delete all search results.
* Go to http://www.skype.com/download and get the latest version of Skype
* Mount the .dmg file and drag the Skype icon to the Applications folder