Windows booting up with no systray.(Need help

My mother just booted up her computer and upon the startup, her wallpaper comes up and nothing else. No applications, no systray, no anything, just the wallpaper. Nothing loads up at all. The processes seem normal, kind of. I'm not too positive what to look for. She told me a bunch of bullshit like "I don't think I have any space left" or "I moved around stuff to make space". There should have been warning before you do that, and I'm not sure that would produce such a problem. Anyways...Any solutions? Thanks.

Like people who ignore the oil light in their car and are then surprised when the engine seizes rock solid.