Do you mean it starts loading windows but never displays the taskbar or desktop icons? Is there a movable mouse pointer on screen? Have you tried safe mode? (keep tapping F8 before windows starts loading). Can be a malware thing - if safe mode doesn't work try hitting ctrl+alt+del when mouse pointer on screen (if I've describled it as is). This should load task manager or a screen full of options, including task manager. Task manager has option to run new job (like the start, run box). Type explorer in there and see if it brings up the desktop.