In Windows XP, open the Control Panel, then double click on the "Sounds and Audio Devices" icon. When that opens, click on the "Sounds" tab, then scroll through the various sounds and see which one applies. You can change the sound to "None" if you choose.. Maybe you're getting a "Blocked Popup" sound in Windows Explorer.. Or maybe it's a "Critical Stop" sound.. Either way, you should be able to find the culprit and change the sound.
Hope this helps.
Grif
If I open up IE6 and go to a page and then hit the back button, there is a familiar click noise. I hear that noise about every 8 seconds in CSS. IE6 is not running, it makes the noise when I minimize source (even though none of the other noises are present.) As soon as I exit (end the process known as HL2.exe) it stops.
Any ideas?

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