Look at the f5 key, it's secondary function (or primary depending on how you set up the keyboard in the BIOS), is to turn the trackpad on and off. you probably hit it by accident. There are loads of posts on various web sites about people installing older drivers and they work for a while, and people returning laptops to manufacturers because the hardware is faulty. I've just spent hours installing and re-installing different drivers, with no success, even following the advice on this page. Then I stumbled across a post on another site that mentioned a hot key combination to enable / disable the trackpad and the penny dropped...