Same thing, exactly happened to me, freaky. Freaky isn't it. Here's the fix. Go into computer>Library>Contextual Menu items - remove any plugins and place on the desktop. Now logout or restart and try to duplicate your problem. My guess is no more problem. If you have more than one plugin, reinstall one at a time complete with restart until the problem returns. On mine, it was the stuffitCM.plugin, which I found out had a patch available. After the patch, no more hair pulling! I spent 5 hours on the phone with Apple to no avail. I found the answer here in this forum. Good luck.
Qfer