Freshly Installed WinXP Pro Fails to show Taskbar or START

I just installed Win XP on a freshly formatted C: drive of an IBM HDD using a slipstreamed XP disk. It appeared to install normally, loaded all the required drivers and configured without problems. But when booted and rebooted several times it shows a window with the standard background, BUT NO TASKBAR nor START BUTTON. The computer is ok because it loads XP normally from the slave drive.
When I run the Task Manager it shows explorer.exe and normal processes, but will not respond to the shutdown option.
Any ideas on what happened and how to fix it?