After running a repair / repair system files, you may receive the subject message. When you click OK, only your wallpaper is visible, the shell, Explorer, did not start.
The repair replaced some updated system system files required by IE 4.0, with the original Windows NT files from the CD.
To resolve the problem:
1. CTRL+ALT+DEL / Task Manager / Application Tab / New Task / "<path1>\ieremove" /i:"<path2>\integrated browser nt.dat" as explained in Q166314.
2. Reinstall your latest Service Pack / Hotfix(s) (don't create another unistall folder).
3. Reinstall Internet Explorer 4.0.
In the future, the proper way to repair system files when you have IE 4.0 installed is:
1. Use Control Panel / Add/Remove / Uninstall Internet Explorer 4.0 and all its components," and then click OK.
2. Uninstall the Windows NT Service Pack (start the Service Pack installation and choose the Uninstall option).
3. Run the repair.
4. Reinstall the Service Pack / Hotfix(s).
5. Reinstall IE 4.0 (consider installing the browser, only).