Hi,
Can you always reproduce the red cross on the client?
If it's caused by the UI layout issue, you may need to delete all the xml files under "C:\Documents and Settings\%user%\Application Data\Autodesk\Autodesk Vault Manufacturing 2010\Objects" and restart Vault, it will help to clear the history information of client UI layout. If this does not work, perhaps restarting ADMS is a way worth trying.
Thanks,
Carol