machine died during windows update installation

I cannot believe my luck - shutting down my computer windows vista says it is installing the latest updates (do not switch off power) and then bang, there's a power cut !

Now when I switch the machine on it is trapped in an endless loop of trying to finish the installation, finding a problem so it restarts. I have tried breaking into windows as the machine boots up but nothing seems to stop the looping.
safe mode has the same problem
bringing up system restore only gives me a choice of rolling back the last 2 checkpoints - and neither will complete without an error.

I'm stuck - and would rather avoid attempting to use a restore OS option unless there's no other way.

Any suggestions ?

There is way to stop this loop:METHOD THREE from this link:The update is not installed successfully, you receive a message, and the computer restarts when you try to install an update in Windows Vista

see also helpful link how to edit registry remotely from WinRE (from post 17)
http://www.vistax64.com/general-discussion/191151-cant-delete-registry-key-2.html

:D Thanks. I managed to stop the machine looping by following this. A side effect was that Windows update then stopped working properly - but Vista's self diagnosis managed to find me a registry download which ran and corrected the problem.
End result is all is now working fine.

Many thanks

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