Ok - turns out, when I re-booted back into Windows I used the "Restart..." option on the "Power Off / Log Out" drop down in Debian.
Also, when I re-booted from Windows I always used the "Restart" option.
This always resulted in no internet in windows.
I just re-booted from Debian using the...
I don't believe I did anything to the hard drive.
And, yes, it could be coincidental but it's one of those where it seems too coincidental!! But then, they always do.
I will do some more investigating tomorrow and post back if I get any more insight.
Thanks for your reply.
I have just tried Debian live from a USB drive as a first time Linux user.
Everything worked fine including internet in Debian.
I then re-started my machine and booted back into Windows and found that I have lost all internet connectivity!
If I boot back into Debian live the internet is working...