Yes... the lines I was seeing were solid black about the thickness of the lines used for track lines but absolutely dead straight across thousands of miles.
However - it is possible that it is some kind of glitch - as the box itself has developed a fault (only just had it a few days) with it's receive sensitivity dropping suddenly by 75% or more .... range went down very suddenly Tuesday PM from over 150 miles to less than 50.
The change was dramatic - from 40 or 50 aircraft in the "My Flights" list suddenly down to 5 or 6 with no apparent reason.(This at about 1500Z- position almost right under RB and about 10 miles N of BHD- a busy spot.)
I thought"damaged antenna maybe" and purchased a new one which arrived today - but still no joy...so after talking to the supplier and W&S(very helpful guy there), the box is on it's way back for them to sort out what has gone wrong.
Hopefully it will get sorted out PDQ and I'll be able to play again very soon!
:(
Dave