I was having problems with explorer.exe using 99% CPU and, having no luck with various efforts to fix it, I decided to format my C: drive and re-install Windows XP as my laptop needed a refresh anyway! I did this using Acer Erecovery i.e. Alt + F10 when booting up, so it re-built to factory settings from the D: drive I believe. However to my dismay the problem is still there, even before installing any additional software after the rebuild i.e. everything runs very slowly, using the keyboard is almost impossible as keystrokes don’t always work, Task Manager constantly shows 99%-100% CPU, and when I shut down it always shows explorer.exe still running and not responding.
How can this be, immediately after a fresh windows re-install?