Consequences of turning off computer during Windows Vista update ("Do not turn off your computer")?

Solution 1:

Likely, the update it is currently on will fail, but you can continue using your computer like nothing happened - You may want to run chkdsk on your hard drive just to make sure there are no problems.

Worst-case usual scenario - It is in the middle of updating a system file / half way through the process and a restart means it is missing as it is does not exist at the moment. However, Windows Vista is quite good at repairing itself and may boot into the recovery mode and roll back the update for you, so you will be out of action for a short while (probably under 30 minutes)

Utter worst case unusual scenario, it is updating a boot file (but not sure how many updates do this) and restarting will give the message "Operating System Not Found" or similar. In which case you will need to put in the original disk and do a startup repair or at very worst case, a reinstall of Windows.

Solution 2:

Is it a Vista machine?

Exact same thing happened to me, only my machine took it upon itself to turn off midway through, totally borked my OS, nothing would boot or update. I ended up running a linux live CD to backup a few files I wanted then reformatting the bugger!