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.

but wouldn't your mother have had windows screaming at her that her disk was nearly full? At least for a time beforhand?