Well, my brother had a laptop of HP(forgot the model). He had Ubuntu 11.04 Natty Narwhal and Windows 7 installed. When ever he used to plug in his power cable, the mouse pad on his laptop stopped working. After the power cable is pulled off, there was no problem regarding such disability. We tested the command:

dmesg

And saw the device record, but nothing seems that Ubuntu got the problem. But in windows, we got no problem. Then we tested the power supply on the charger and found that the Ubuntu need sufficient amount of power that couldn’t be provided by the charger.
Also, we tested the PC with my HP charger, and found that it was working fine. So, you may say what’s the point that it was solved. But I am waring you about the change time of your charger. Or just use the windows and be a dumb.