I ran CCleaner V7 and caused major failures

where many of my applications did not work. Have been doing reseach into the issues and it looks like the tool either corrupted or removed Windows 10 file..

Did you use the Analyzer (actually a Duplicate Finder) and ‘Batch’ delete everything that it found?

If so then you will almost certainly have deleted some duplicate files that the Windows System needs, and some duplicate files that some apps need.

Having already done the damage your options now are:

If you have a current system backup, or a Windows restore point, then you can try restoring that to get the deleted duplicates back again.

It will depend on just what type of backups you make. They should be in a full System Image, but probably not in a Data/Files only backup.

If you don’t have those, or they don’t work then running DISM and SFC should repair the Windows system.

If you are having problems with any particular apps then you may need to repair/reinstall them, depending on if the app has a repair option or not.

After 2 PC towers being killed off in 48 hours I am not sure what has been going on. Both PCs would not boot reporting boot errors. Unable to boot from HDD, DVD or USB to recover. I initially held CC7 to account but the news today reports MS update problems causing similar outage. After eventually managing to recover one of the towers yesterday I receive an alert from my AV provider this morning. It reports that my system resources are overloaded, registry issues etc.

yup, used the delete duplicates program and deleted ~50 G. Thanks for the advise I’ll give them a try

Yes. there are problems with the monthly MS updates this month, as well as with the update to Windows11 25H2 which is currently rolling out.

It all makes things “interesting” (more awkward) when trying to work out just what it is that is causing any particular problem.

unfortunately, we could not repair, so we re-installed Windows, problem fixed