The Little-Known Boot-Repair Command
I know what you're thinking: If I could restart my f&%$#&^ing computer, I wouldn't need no stinkin' backup disks. I realize this is circuitous reasoning, but if you can't get your computer to boot up, then you've got a boot problem.
True, Vista no longer relies heavily on a boot.ini file. (Indeed, it no longer has a boot.ini file) Rather, Vista maintains a sophisticated tally of what it's supposed to load at startup in something called a Boot Configuration Data store. The BCD is more precisely a list of boot options; that list is made up of Boot Configuration Data elements and objects.
It's a vast oversimplification, but when you can't boot up, the problem typically involves a bad BCD store. (At a lower level, your BIOS could have trouble loading and/or the Master Boot Record could be corrupted.)
On the path to Bootrec, the "System Recovery Options" box should identify your current Vista installation as the OS designated for repair.
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Of course, most crashes can be solved by a simple restart. However, rarer and serious incidents may corrupt the Boot Configuration Data file and render Vista unstartable. From my research, it appears that most problems like this occur when people have set up, or tried to set up, dual-boot systems.
How do you know there's bad Boot Configuration Data? When you start up and get an error message which reads: "The Windows Boot Configuration Data file is missing required information."
Fortunately, if and when this occurs, Microsoft has a tool to help. With Vista, it's called Bootrec, rather than the Bootcfg moniker used when Langa popularized it for XP. With Vista, the command sequence also is slightly different. However, the ultimate goal is the same: Repair a bad Master Boot Record, boot sector, or BCD store, and get your system to restart normally.
Interestingly, when I typed "Bootrec" into Help, I got "0 results. No matter; the real scoop on its operation is contained in two Microsoft Knowledge Base notes [(LINKS here and here)].
The easiest path to Bootrec repair is to insert your Vista installation disk and fire up your PC. In reality, you might have to start your machine twice, if you can't get the disk into your drive fast enough to get it to boot from the drive. In such a situation, turn on the PC, insert the disk, and then turn the machine off. When you restart it, you're likely to get the message, "Hit any key to boot from CD or DVD." My advice: Hit any key.