After trying to update a poorly operating computer under the Norton diagnostic suggestion the computer has crashed. I can't get past a black screen with the text scrolling continuously that says:

!!0xc01a001d9256/93193(/registry/machine/COMPONENTS)

What have I done? What can I do to fix this? I've tried turning the computer off and starting again over and over. It will only "start up" and go through the process up to the point of scrolling through all the files and then sticks on the above code.

Any help will be appreciated. I'm (obviously) writing this message on a borrowed computer.

You need to ensure your PC is healthy before attempting most updates:

After trying to update a poorly operating computer

That can often be a serious mistake as the following explains – fixing your issues may then often be impossible:

!!0xc01a001d 9841/94009 (\Registry\Machine\COMPONENTS\Derived\Data...)

Upon inspection the notebook will not startup in safe mode and hangs the line Loaded: \Windows\system32\drivers\crcdisk.sys. My diagnosis given that service pack 1 makes significant changes to the system which could mean that there could be hundreds of errors beyond this one if SP1 got disrupted half way through installation is going to be to take out hard drive and use me SATA to USB cable to access the personal files on the drive so I can back up his personal data and then use the repair disk to fresh install Windows.

My guess on why this has gone wrong would either be firstly antivirus software detected intrusion to Windows core (eg SP1 making changes) and stopped the intrusion (eg stopping SP1 half way through). or Faulty RAM where SP1 went to access a faulty area of the RAM and shutdown half way through install or faulty hard drive sector/s eg SP1 tried to read/write data to dead sector and failed.

You can research further, here:

"0xc01a001d9256/93193/registry/machine/COMPONENTS" "black screen" - Google Search

You could also try this: To start the computer using the last known good configuration