Windows 8 Update 1 release notes
Windows 8 Update 1 release notes
Check the installation files and ensure they're properly placed in the Windows Update folder. If the issue persists, it might be a pending update—wait for the next release or contact support for assistance.
Click the taskbar with the right mouse button, select Properties, and under the Navigation section, check the option "When I sign in or close all applications on a screen, go to the Desktop instead of Start."