Have you ever tried logging on to your computer and received the following notification?
"Windows cannot load the profile and is logging you on with a temporary profile."
One thing that can cause this to happen is corruption of your local user profile. Such corruption may be caused if your computer didn't log off or shut down properly during your previous session. If this happens, Windows copies your local profile to a hidden location, creates a temporary profile for you, and logs you on using this temporary profile.
This happened to me once on a standalone (not domain-joined) computer I was working on, and when I tried to open my Documents folder all my files were gone! Why? Because the Documents folder is part of my user profile. You can imagine how I began to panic (though I did have a fairly recent backup I could fall back on if needed).
I resolved the situation by logging off and restarting my computer, and when I logged on again, this time I was logged on using my local profile. Fortunately the profile corruption was minimal and Windows was able to rebuild my profile.
Bottom line however is that this is a good lesson for ensuring you make regular backups of standalone computers you are working on, or on domain-joined computers where you don't have roaming profiles implemented. And of course in a domain-joined environment you should use Folder Redirection to redirect your Documents folder to a network share for added safety and centralized backups.
If you have feedback concerning this tip, I'd love to hear from you.