Unfortunatelly I have a Toshiba Satellite with Windows Vista.
I have lots of games in my laptop but I also use it for work.
My laptop beeps now and then.
I started having problerms with my games, and after several hours and days dealing with unskilled so called "techs", I finally could talk with some real techs.
They found out that my laptop OVERHEATS BIG TIME, especially playing games, or using HTML5 programs for design. That causes the computer to slow down until is freezes completely. They said that eventually it will stop working and die.
I heard those beeps many times while playing games especially. I asume that your computer is trying to warn you: hey, I'm overheating or too much effort to process. Shut me down or I will die in minutes,
It if helps you, design programs and games seem to need lots of processing and you can hear you computer fan making weird noises.
The overheating of Vista is one of the reasons Microsoft dropped Vista for good: no real fix for it.
I recommend that when you hear the beep, shut you computer down for sometime until you can feel your computer is cold again.