The touchpad on my wife’s new laptop was acting erratic. After doing some research, I found that this has to do with the power supply. However, there’s nothing wrong with the power supply, per se. I mean, it does what it’s supposed to do – charge the laptop’s battery. But it somehow interferes with the touchpad. The erratic effect, in fact, would only occur when the power supply was plugged into the machine.
I found this bit of information quoted from Wikipedia. I was going to save the original link to the Wikipedia article, but then I found out on Wikipedia’s “talk” page, that this content had been deleted. So, I’m putting here on yet another place on the Internet so that this precious information is not lost! Here it is:
“If the computer is powered by an external power supply unit (PSU), the detailed construction of the PSU will influence the virtual ground effect; a touchpad may work properly with one PSU but be jerky or malfunction with another (this does not imply any electrical risk; a delicate capacitive ground, not a contact ground, is at issue). This has been known to cause touchpad problems when a manufacturer’s PSU, which will have been designed to work with the touchpad, is replaced by a different type. This effect can be checked by touching a metallic part of the computer with the other hand and seeing if operation is restored. In some cases touching the (insulated) power supply with some part of the body, or using the computer on the lap instead of on a desk, can restore correct operation.” (Wikipedia)