If the beep seems to be coming from inside your computer, and is a single tone, then that probably means there's some sort of crittical hardware failure and the system is shutting down to protect itself.
My first guess in such a situation, would be a CPU temp alarm. For whatever reason, your CPU is reaching dangerous temperatures, and if the system didn't shut down, it might be damaged (and you can't repair a CPU, only get a new one). Check to make sure your CPU fan isn't clogged with dust, and that it's seated properly. You might even consider getting a more efficient heat sink fan unit, and some better thermal grease.
I'm runing XP Home & periodically after about an hour online I get a short single beep sound just before a system crash. Later I get a long single beep. Has anyone had this problem? Does anyone know what the beeps means?
Thanking you all in advance,
Aleks.

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