I'm back.
Been busy.
I took the two faulty boards to someone else.
He has many Arduinos.
All of them work. He can flash them and all that.
Plug mine in... Nothing.
As the chips are DIP, we swapped them.
I have forgotten what exactly happened, but one weird thing was that if we put the "128"(?) chip in where the 328 should be, it can be flashed.
But with the original (and other same) chips, it simply refuses to flash.
We tried re-burnign the boot loader, but that too failed.
WRT the "missing" DLL file:
I looked on my desk machine - which wasn't connected to the net at the time. There isn't one there either.
I was sort of hoping to find it and copy it. Alas.... That isn't going to happen.
The other person tried your GUI and it wouldn't flash MY Arduinos.
It would flash others.
Two boards, bought from DIFFERENT SHOPS who have DIFFERENT SUPPLIERS, both seem dead.