A personal cabinet is, in PDMLink, a backgound object which has a specific domain associated. There is a 1:1 relationship of Personal Cabinet to each User account. This is created automatically when the user is created. It is the users personal domain where the system stores the working copies of objects a user checks out. No other user, with exception of the site level admin group, has any permissions in this cabinet domain. This is how the system "locks" checked out work from other users. The cabinet construct comes from Windchill Foundation where cabinet objects were the primary mechanism for managing all business objects.
The site admin can access the Personal Cabinet Administrator. This will display the personal cabinets of deleted users and give the option to check in all work and to delete those personal cabinets. See the admin guides for more info.
As far as your error, I've seen similar, though I'm not sure exactly the same, messages when varous things occur with admin users. Keep in mind that when working with admin tools such as Type, WF, LC, etc., when you edit these, objects they are checked out to the personal cabinet of the admin user. If you forget to check them back in, you will be able to see, and often use your latest edits, but no other user will be able to. This can, and has, resulted in serious data base issues, but it is common enough that Tech Support can usually provide recovery tools. Particularly this is a problem if more than one physical user uses an admin user account. Since they share the same admin personal cabinet, but don't know what each other are doing, you can get some strange behavior. So....... DON'T DO THAT!
Tech Support should be able to resolve your specific issue for you.