I have a strange problem with my wife's laptop in that often when it comes out of sleep mode the keyboard and touchpad (Alps) stop working. Plug in a USB mouse and keyboard and they work fine so it's not the machine which has crashed. Rebooting the computer makes everything work again.
As is usually the case though it doesn't do it every time so if I send it back it'll probably be fine when they test it and then they'll claim there is nothing wrong with it
I'm going to try a factory default reset tonight to see if that helps as to me it smells like a software issue rather than hardware.
It's an Acer 5738 running Vista SP2 all up to date.