That´s why one should be careful with updates. If there aren´t any issues, updating the system could not make it better

If you are sure you updated only the hotkey driver, the manually reinstalling it should fix the problem. For this purpose go to Lenovo website -> support and download the hotkey/OSD driver. Uninstall the current one, reboot, run the .exe, it will
only unpack the driver installer on C:\Drivers\Something (note exact location before starting the unpacking), go to that folder and run setup.exe, reboot. Now, it should work. If it doesn´t, return for more detailed instructions
Marin
IBM Lenovo Z61p | 15.4'' WUXGA | Intel Core 2 Duo T7400 2x 2.16GHz | 4 GB Kingston HyperX | Hitachi 7K500 500 GB + WD 1TB (USB) | ATI Mobility FireGL V5200 | ThinkPad Atheros a/b/g | Analog Devices AD1981HD | Win 7 x86 + ArchLinux 2009.08 x64 (number crunching)