I did a trip back from Shrewsbury to home (near Horsham, West Sussex) last night.
On the M25 near Heathrow, my 765 had a funny turn.
Instead of keeping me on the M25 motorway through J14, it wanted me to go up the slip road, round the roundabout and back down the "on" slip to rejoin the motorway. I don't think it would have been either faster or shorter!
Map versions are CN Europe NT 2011.30 3D and CN Europe NT 2011.32
I have experienced this same problem on the M1. And if it is of any comfort to you, have experienced this also with an earlier Michelin via sat nav and also with Tom tom in France.
I had reported this to Michelin who could offer no solution since in checking out their mapping for a particular road junction there were no errors in the software.
I wonder if somtimes spurious satalite reading cause this sort of misinterpretation.