I recently got my hands on two Lenovo Thinkpads. In both cases I’ve noted the touchpad would randomly stop working. At first I thought I wasn’t pushing hard enough, so I changed the touch sensitivity to as light as possible. No change.
Before making any calls I decided to see if I was alone. I not. It seems this problem is driver related and occurs on just about every model of Lenovo. Disappointing.
A bit of searching and forum diving get me to this post[1] from a Lenovo staff member suggesting that you roll-back the driver for the touchpad until “engineering has provided an updated version of the driver in order to fix this issue.”  Furthor down in the thread, another poster links to a driver from Synaptics[2], the manufacturer of the touchpad.
[1] http://forums.lenovo.com/t5/T400-T500-and-newer-T-series/T410-T400s-Touchpad-hangs-quite-often-SynTPEnh-exe-hangs-at-50/m-p/281238#M32110
[2] http://www.synaptics.com/support/drivers