Windows Vista, both the RTM and Service Pack 1 versions, can lose installed drivers in scenarios in which the computer is started via the Last Known Good Configuration feature. According to Microsoft not only Vista RTM/SP1 is affected, but also Windows Server 2008 RTM/SP1. Machines booted with the Last Known Good Configuration feature can have some .inf files removed from the %windir%\inf folder. In this context, the 
operating systems  will also lose the installed drivers associated with the .inf files.

“These .inf files correspond to the drivers that are included with Windows. If you try to install a new device that uses an .inf file that has been deleted, you may receive an error message that resembles the following: “Driver not found.” If you try to reinstall the same version of driver that was originally serviced, the devices that use that .inf file may not work correctly,” Microsoft informed.

The updates can be accessed through the links below:

• Update for Windows Vista (KB953631)
• Update for Windows Vista for x64-based Systems (KB953631)
• Update for Windows Server 2008 (KB953631)
• Update for Windows Server 2008 x64 Edition (KB953631)
• Update for Windows Server 2008 for Itanium-based Systems (KB953631)

Source:→ Softpedia