I encountered an error when I tried to run the Windows 7 built in boot time optimization via command prompt, “defrag c: -b”, saying that registry entries for boot time optimization was missing and that boot time optimization could not be performed. After a fresh install, the registry entry isn’t created yet. Apply this ‘fix’ if you don’t want to wait for Windows to make the entry later.
Should work for Vista. Not sure about XP.
To fix this, I created in my registry as follows: