A friend's computer froze when trying to run the Malicious Software Removal Tool which arrived through a Windows update. When we restarted it, before any Windows screen appeared it said "Disk read error. Press Ctrl-Alt-Del to restart." and when we did, it restarted very slowly. It had been freezing from time to time before, but it's never given the disk read error before.

I realise we need to deal with the freezing as well - but we'd better do this first! Is the freeze likely to have caused the disk read error - and if so do we need to go back to the last known good setting?

welcome to PCHF JDW,

Boot using the WinXP cd and use the recovery console (hitting R when it asks). IF and only IF you get the dos based screen AND you get something like:

1. C:\WINDOWS

Please choose which windows you want to use: 1

Or something like that. If you do, then type 1 and hit enter, it will ask for your administrator password which I hope you know. Then at the command prompt enter: chkdsk /r
The /r switch tells chkdsk to scan the entire drive and recover any bad sectors. Depending on the size of your drive this could take a REALLY long time. Once that is all said and done. Reboot the computer and you should not get the error. It's up for grabs how long this fix will last, so far it seems random to me.

Right, I'll try that when I'm next there - thanks. So do you know if having the computer freeze when running the Malicious Software Removal Tool can cause the disk read error? I ask because, if the error's because of that freeze, I can disregard the error when trying to find the reason for the freezing.

And I presume we ought to backup the hard drive before doing this!

it would be wise to back up. but check disk should fix your error problem. your hard drive might be starting to go.