No Desktop Pop Up Alert for Low Battery

I own two new Dell Laptops, one a Precision workstation and the other an everyday Latitude, both running Win 7 Pro. Both have new batteries, so that's not an issue. Please do not suggest I check my battery. My system power settings are correct for both AC power and on battery, so that's not a problem either.
I replaced a Dell XP machine and an older Compaq machine running a Win 7 32 bit upgrade from Vista. Both of the older machines, upon reaching the preset low power settings limits, would open a pop up window on my desktop and alert me to either save my work and shut down or plug in the power cord. It would supersede and open on top of any work windows I had open. Both of the two new machines have no such pop open alert window and my computer often hibernates unexpectedly. Not a crisis, but a real pain when in the middle of work. I know that there are taskbar icon notifications and audible alert tones, but neither is useful for me. I must keep my computer muted when working and my taskbar is set to extreme hi-res with small icons, so you can't really notice the taskbar alert when concentrating on your work. Is the desktop pop open alert window gone forever, just turned off somehow, or what? Some one please advise. Thank you.

PS - I should explain. When I write "concentrating on my work", I mean that I create complex 3D solid models for expensive tooling and manufacturing businesses in a program which often is on top of the taskbar for screen optimization. They require my full attention and, as the result, the taskbar low power notification is pretty much useless for me. The desktop pop up window, which doesn't now open, worked great.