*This* is what Windows update has been reduced to

“Size: 149 KB - 571 KB
Install this update to prevent an issue in which you may receive a “stop 0x7e in AEC.SYS” error message on a computer that is running Windows XP Service Pack 2. The error may occur during startup, or after the system has started. AEC.SYS is the acoustic echo canceling driver. After you install this item, you may have to restart your computer.
More information for this update can be found at http://support.microsoft.com/kb/900485


Since when is an acoustic echo-canceling driver considered part of the operating system?

Why the heck does it have to be a driver?

One that produces a blue screen with a numbered error code?

One that can bring the whole OS to a grinding halt?

Why does it need to be loaded at startup?


The AEC system driver (aec.sys) supports full-duplex DirectSound applications by implementing AEC (acoustic echo cancellation) and noise-suppression algorithms in software. For more information, see DirectSound Capture Effects.

In Microsoft Windows XP and later, you can expose your audio device’s hardware-accelerated capture effects to DirectSound applications. In addition, the AEC system filter (aec.sys) provides software emulation of AEC and NS effects.
AEC System Filter

This specific fix is a random timing bugcheck that can happen when using two-way audio (e.g. netmeeting, messenger, etc.) It is a random event that could happen at any time. If you hit it, and reboot, you might not ever hit it again; or you might hit it next month, or in a few months, or the next day.