ddjkdg-
I think you have a software problem, not a hardware problem. I have the Visioneer 8900 and have had a similar problem when using the Paperport software that came with the scanner. Whenever I first attempt to scan through Paperport, I get the "unlock" message. Clicking OK doesn't help. But, if I go to the other scan program that I have, do a scan and then attempt to use the Paperport program again, it works fine.
Another thing I've noticed is, if I have my scanner already turned on when I start my computer, I don't get the "unlock" message and it works fine on first scan with Paperport or any other program. But, if I turn my scanner on after my computer is already on, then the "unlock" message appears.
I haven't really investigated for any cures to the "unlock" message since I was able to get around it, but there must be an answer.