Hi,

Thanks for patience, advice and perseverance!! Sorted.

Despite my thoughts, it was AV! In case anyone gets this problem, here is the solution for me. As instructed switch off all AV, especially Windows SmartScreen. That was the one that caused the initial trouble even though I had switched of Windows Defender. (I use Norton who caused no problems here). I was trying to use MS Edge but decided to try Internet Explorer instead. Initially the package would only part download with the warning "the publisher of this programme couldn't be verified."
There are internet guidelines on how to adjust the IE setting to remove this warning so use those. Then I downloaded the files again. The download did get interrupted and had to be resumed several times and eventually I had two nice new files!

As is often typical in the world of computers, I had no problems downloading when I purchased the 757 for P3DV4. I have changed nothing on my PC so no idea why. And typical in the world of flight simulation a few hours of my life consumed, hours which I will never get back!   Happy New Year to all. Looking forward to giving this aircraft some serious schedules!!

Regards,

Keith