Mouse pointer freezes every 2 seconds

Hello all,

Occasionally (I would say one out of three times), when I use my notebook's touchpad, the mouse pointer freezes for a fragile of a second, once every 2 seconds. This freeze breaks the mouse movement or scrolling in the middle, and during that time I have to fight to get my mouse pointer to the place that I want. Doesn't happen if I use an extenral mouse. Any ideas?

I'm using a new HP Probook 4540s with 8GB RAM and 7200rpm hard drive.

Thanks!