Windows problem - HELP!

I was working on some code last night, when all of a sudden my windows start bar dissappeared, and my desktop showed the desktop image but no icons. Now when i boot up it seems to boot fine, but stops at the point where the desktop image is shown, and the startbar/desktop just never appear. CTRL ALT DELETE allowed me to manually start my virus scanner, but that found nothing, and i can’t work out what else I can do.

Has anyone got suggestions as to what has happened/how to fix this? I’m tearing my hair out. Was up till 3 am trying to fix it with no luck. The exact same thing happens in safe mode too.

Oh, one time i rebooted the desktop and everything showed fine for about 5 seconds before it all dissappeared.

Help!