Thanks. Yes I will look on their forum, but I do not hold out much hope.

Anyway, I used TimeMachine.

It asks for a password. I still cannot logon and still get the same error message. Further reading advises that I should set a password in Time Machine preferences. There is nowhere to do this!

I have also read through this article.....

Mac OS X 10.5: Security tips for using Time Machine over a network

The article also advises that a password be set in Time Machine preferences.

As far as I can see it is not a QNAP problem as the root of the problem is on the MBP when starting to run the application especially with regards to password requirements.

Edited. I went back to basics and started again and using TimeMachine again I reset the password yet again and it worked this time. So not a QNAP or Apple problem, it was my problem. Thanks again.