Okay I set up a site for a client with Contribute, and I had a trial
version of Contribute myself to set it up. Now I have MX 2004 which I think
doesn't have Contribute capability. So when I changed something on the site,
the client found they couldn't alter anything on that file because it was
locked by me, even though I had closed the file off the previous week.

No problem, I thought, I will delete the .lck files using WS_FTP, which I
have done, and for a while things seem to have worked fine. Until last week
I deleted all of the .lck files, after I had done some major work, thinking
to save the client a recurrence of the problem. Now when the client goes to
update the site she gets this message:

You can't publish this draft because another user has removed your lock on
the file. Select File > Publish as New Page to publish your draft with a
different filename, or click Cancel to discard the draft.

Okay so I also went through the site deleting all .mno files. But the client
still gets this message. What can I do?