Could you please better describe the sound you are hearing when the machine does this.

I am having a similar problem with same said machine only the sound I hear is not a Beep... it is the sound a computer makes when  you connect or disconnect hardware devices.

Periodically I will hear the sound like I am connecting a new device and then seconds later I will hear the disconnect sound as well. It affects the current window by forcing me to re click the window I am working on or in, which for me is not as annoying as the constant connect and disconnect sound.  

I have a had this issue and an issue with the integrated web cam since purchase of this XPS. For the web cam issue, the cam would fire up on first use just fine, but if the computer went into sleep mode, or if I turned it off. The cam would then give me one of two error messages "no device found" or "the application is being used by another source" ...even though neither were true.

I called Dell about this issue and the rep took control of my computer, reinstalled the cam drivers but still did not work. Then she suggested I pull the power cord, pull the battery, and hold the power button for 15 seconds....(this did work and I was happy, UNTIL I put the computer to sleep again and the same instance occurred.)

I did not wish to send the machine back for because of a cam issue so I went and bought a new external cam made by HP. After the installation of the HP cam, the integrated cam has worked fine.... go figure.

However it was only after this device was installed that I now get that annoying Hardware connect and disconnect issue.

Not sure if this helps you or not, but I thought I would share my experiences of issues with this New XPS 17

Yes I think the beep is the same beep you get when you plug in a usb device or something.  I didn't realize that before but I think you are right.  I will have to do some experimenting.

I have this problem too and have tried in vain to look for a solution. The beep is not the same as when you add or remove a device, it is more metallic and like  a warning.

I have experimented to see if updating mouse and touchpad drivers helps but it doesn't. It is not about the erratic movement of the cursor, it is indeed a switch of focus from window to desktop.

Does anyone know if Dell even acknowledges this problem ... and is looking into it?

I have a Dell XPS that loses focus at random, but it doesn't exhibit the beep when it happens.

I had thought it was a Windows 7 problem so I had been working on it here:

http://answers.microsoft.com/en-us/windows/forum/windows_7-desktop/windows-lose-focus-seemingly-at-random/43482cc3-cad3-499f-882c-a436b3ec4798

but now I am figuring out that this may be unique to Dell XPS machines.

I turned off the keyboard ambient automatic sensor and that solved the problem for me.

commweb-ps3.us.dell.com/.../19393785.aspx

EEEEEEEEEEEEEK!  Yes I HATE this.  I also am thinking of trashing the computer.  It happ   ened again JUST NOW TWICE!!!

After months of trying every idea I've read I saw the post about the ambient light sensor.  That fixed the problem!  Small price to pay losing the sensor since the computer was unusable at times.  Thanks to whoever figured this out!

I bought mine last night. It does the same thing. It also chirps endlessly. Needless to say, it is going back.