Problem Summary: When a user selects and executes the FindAllMyObjects query in the Web Console, the results display includes the User object for the user who executed the query, along with all other objects owned by the user. If the user inadvertently deletes this object, major problems result: the user can no longer perform any actions on objects that he or she published as that user, and he or she must perform user registration again in order to publish more objects. The FindAllMyObjects query should not display this User object. Only the GetCallersUser query should display this object.
Workaround: Be careful not to delete your own User object.