I have no problem with Outlook Express on my XP Pro system nor my friends XP Home system.

You may want to read this

Windows Explorer is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface for accessing the file systems. It is also the component of the operating system that presents many user interface items on the monitor such as the taskbar and desktop. Controlling the computer is possible without Windows Explorer running (for example, the File | Run command in Task Manager on NT-derived versions of Windows will function without it, as will commands typed in a command prompt window). Located in the C:\Windows directory, it is sometimes referred to as the Windows Shell, explorer.exe, or simply “Explorer”.
http://en.wikipedia.org/wiki/Windows_Explorer

Especially this item

It is also the component of the operating system that presents many user interface items on the monitor such as the taskbar and desktop.