Michael,
I think I might have a threory on some problems folks are having with browser crashes (mainly Netscape). Bare with me.
First, the pop ad at the bottom of a typical FlyerTalk page that now has the annoying sound file. I got it again today. It is an ad for "netstocks.com." It is NOT a normal animated GIF. I went to right click on the ad to get the URL for you, and instead of getting the usual properties window, I got a "FlashPlayer4" control panel.
So, my theory is that if visitors don't have the FlashPlayer4 plug-in in their browser, it is causing it to freeze or crash.
That's my theory. Whatever it is it's annonying as heck!