When this happens, press CTRL+ALT+DEL and start Task Manager. If Explorer.exe is not a running process, try starting it.

If this does not solve the problem, you most likely have an old version of a required DLL in %SystemRoot%.

Windows 2000 uses the same methodology to locate a DLL as windows NT. Since Explorer.exe is located in %SystemRoot%, any old DLL, located in %SystemRoot%, would be found before the correct version.

My guess is shdocvw.dll, but any of the following other files in %SystemRoot% can cause problems:

Browseui.dll                              Comctl32.dll                              Comdlg32.dll                              Mlang.dll                              Ole32.dll                              Oleaut32.dll                              Shell32.dll                               Shlwapi.dll                               Urlmon.dll                              Wininet.dll
To fix the problem:

1. Press CTRL+ALT+DEL and start Task Manager.

2. Select New Task (Run) from the File menu.

3. Switch (CD) to the %SystemRoot% folder.

4. Rename the offending file to .old (rename shdocvw.dll shdocvw.old).

5. Shutdown and restart your computer.

NOTE: The newer versions of the above files will be located elsewhere on your disk.