During an attempt to update a package source with a service pack I had to kill the DSM explorer mid copy... bad idea. Any further edits of the package including deleting/sealing etc. gave me the following error:
The software is currently locked. Please retry the operation, if possible [SDM000103]
The lock cannot be removed from the client end (rebooting PC) so the method to resolve this is to do a CAF restart on the DM (Domain Manager).
caf stop
caf start