I already mentioned that the programme (Cubase SX) works fine with the on-board hard drive, and the other two external drives. Therefore I don't see that it can be anything to do with out of date soundcard drivers.
With respect, I have been working directly with 3 different outboard hard drives for several years, without problems.
All the ASIO settings and MAudio Delta 66 settings are unchanged.
What I need is someone who knows that precise error message that I have quoted, and the precise remedy.
I record live gigs on a Zoom H4n, dump the stereo pair (and tracks 3 & 4 after making them into two mono files) into Cubase SX, and mix them.
Anything done/saved on other external drives works fine. Anything from the new 3TB (Intenso) hard drive throws this error message upon first attemt to play back anything in Cubase.