Question : Repair installation when unable to start Vista

I have a PC that lost power before the shutdown process completed.  Now it won't boot - even in Safe mode as the System registry hive is corrupt.  Is there any way to do a repair install of Vista if it is not possible to boot into it ?  Are there any other alternatives for restoring the corrupted registry file to enable a boot ?  

Answer : Repair installation when unable to start Vista

Have you tried inserting your Vista installation DVD and running Startup Repair, as detailed on this page:

http://www.bleepingcomputer.com/tutorials/tutorial148.html
How to automatically repair Windows Vista using Startup Repair

What is Startup Repair?  This Microsoft page has a great deal more information about that:

http://windowshelp.microsoft.com/Windows/en-US/Help/5c59f8c1-b0d1-4f1a-af55-74f3922f3f351033.mspx
Windows Help and How-To:  Startup Repair: frequently asked questions

Startup Repair is designed to detect operating system startup problems and troubleshoot any found and correct them with little user interaction.  It can repair problems such as:

- missing or corrupt drivers
- missing or corrupt system files
- missing or corrupt boot configuration settings
- corrupt registry settings
- corrupt disk metadata (master boot record, partition table, or boot sector.)

When the Startup Repair Tool has taken control, it analyzes startup log files for clues about the source of the problem and launches diagnostic tests to determine the cause. If it determines the cause of the failure, it attempts to fix the problem automatically. After successfully repairing the problem, it will reboot the system, and notify the user of the repairs, filing a detailed report in the Windows Vista event log.

If the Startup Repair Tool can identify the cause of the problem, but can't repair the problem by itself, it will provide access to a set of tools that you can use to manually troubleshoot the problem further.  One of these is the Bootrec tool described below.

If the Startup Repair Tool cannot identify or repair the problem, it will roll back the system to the last configuration that was known to work (Last Known Good Configuration.) Again it will add detailed information about the problem to the Windows Vista event log.