what is the last known good configuration ? and what is the use of that where is the last known good configuration is stored in registry?

Looking in; HKEY_LOCAL_MACHINE\SYSTEM\Select you'll find the D-Word values for "Current"=dword:00000001 "Default"=dword:00000001 "Failed"=dword:00000000 "LastKnownGood"=dword:00000002 CurrentControlSet is volatile and will always be an image (at boot) of what's defined in ControlSetx where x = the value of "Current" Choosing last known good boots the system with the control set that last successfully booted your system. Control sets contain system configuration information such as device drivers and services.Regards, Dave Patrick .... Microsoft Certified Professional -Microsoft MVP [Windows]

It's a Windows startup option that uses the most recent system settings that worked correctly. Every time you turn your computer off and Windows shuts down successfully, important system settings are saved in the registry. You can use those settings to start your computer if a problem occurs. For example, if a new driver for your video card is causing problems, or an incorrect registry setting is preventing Windows from starting correctly, you can restart your computer using Last Known Good Configuration. http://www.petri.co.il/last_known_good_in_windows_2000_xp_2003.htm Santhosh Sivarajan | MCTS, MCSE (W2K3/W2K/NT4), MCSA (W2K3/W2K/MSG), CCNA, Network+ Houston, TX http://blogs.sivarajan.com/ http://publications.sivarajan.com/ This posting is provided "AS IS" with no warranties, and confers no rights.