A few month ago, I used the system restore disk to reset my old Dell Inspiron 1570 notebook. Since then, the powersaving functions (suspend and hibernate) didn’t work properly: every now and then, the notebook won’t wake up (or, to be more specific: it sounded like it did wake up, but the screen stays black).
I never put much effort into solving this problem, but recently I received my new Latitude 6430u ultrabook, and it turned out that it has exactly the same problems.
Luckily, I found this review which guided me to the origin of this behaviour: the pre-installed “Intel PROSet/Wireless Software”. I uninstalled this software (for the Inspiron I had to re-install the Wifi driver, and for the Latitude I had to re-install the bluetooth driver afterwards), and all my problems where gone…