LoadComplete displays this message when you are trying to add a new or existing item to your test project, but the project’s or project suite’s file, or the file of one of the parent project items was changed outside of LoadComplete. The addition of a new item can overwrite changes made to these files by other users. To avoid that, LoadComplete re-loads the parent item or project, or the project suite and updates their state in memory (at that, LoadComplete may need to close some opened editors). After that, you have to repeat adding your item anew.
See Also
Sharing Projects Among Several Testers
About Test Projects and Project Items