when the desktop does not appear, then press crtl+alt+del together to bring up task manager, then in file/new/ type in explorer.exe and your desktop will come back. Sometimes depending on what is going on in the background the desktop will be slow to appear, so I have to see what is running and cancel it.
you need to run chkdsk with the /r parameter either from the recovery console or from the command prompt, you should do this whenever there has been an ungraceful shutdown.