I have a HP Compaq nx7400 laptop that I have recently updated Windows 7 Professional N. Initially I was running Windows XP Professional on the same hardware. The OS change was a clean install and not an upgrade. Soon after this OS change, I started facing a weird problem. I was unable to precisely point the mouse on any screen object using the laptop's touch pad. As this did not happen often, I triaged the problem and found out that the mouse behaves weirdly only when the laptop battery is charging. If I unplug the power cord, the mouse problem is instantaneously resolved. Plugging in the power cord invokes the issue again. However this issue does not occur when the laptop battery is fully changed and the power cord is still plugged in. I have installed all latest device drivers from Windows Update and HP website, but the problem still exists.

It should be the touchpad driver issue. The Windows 7 system build-in touchpad driver is not compatible with the hardware. From HP website I found that the latest drivers are for Windows Vista. HP Compaq nx7400 Notebook PC - Download drivers and software - HP Business Support Center Important Note: Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information. You may try the touchpad driver for Windows Vista. If this driver does not help, you may need to wait for HP to release Windows 7 compatible drivers. In this case I suggest you contact HP support for more information. Contact HPArthur Xie - MSFT