Horse that stops and wont move

Question
QUESTION: I have a young mare that stops for no reason then refuses to move. It is the same either going away or towards home, and in company or alone. She will lunge longrein and lead ok its only when being ridden. I live in France and they break them at 2 here,she has a very lovely tempament it is only this problem, she puts both front feet out and refuses to move even if there is something coming towards her. Please hjave you got any ideas? Have tried turning her with no success!

ANSWER: Hi Anji,
      Could I begin by asking you a few questions? It might be helpful if you could tell me her age, breeding, size (height and build), how long she has been broken, how long you have had her.
      It might also help if you could provide more detail on the history of the problem ie. when did it start, does it happen every time she is ridden, how long into the ride does it occur.
      I presume that when this has happened in the past, you had to dismount, and lead her. I am wondering if she would lead immediately, without any sign of lameness or stiffness.
      I apologise for all the questions, but I think your answers could make it easier to work out what is going on. The first thing that came to mind, on reading your mail, was some sort of physical problem, but that is no more than a guess at the moment. I am hoping that your answers might enable me to come up with a more definitive answer.
   Slan,
         Brendan

---------- FOLLOW-UP ----------

QUESTION: She was 3 on the 24th may this year, a cob normande an in between build weighs approx 550kgs she was broken just after xmas last year and I have had her since april. It is now every time we go out and yes she will lead straight away no signs of anything wrong. The ride should take about an hour but sometimes it takes 2 hrs to get 1km, hope this is of help and lok forward to your answer.

Answer
    Hi Anji,
  Thank you for your mail, unfortunately it doesn't contain any further clues, so I am still at the fishing stage. Initially I had been thinking in terms of a touch of azoturia, or even laminitis, but they seem to be out of the picture now. We know that it has to be a physical or mental issue,so the physical is the obvious place to start.
  So far she has only done this after having had a rider on her back for some time. I wonder if she could have a low grade back problem that only becomes obvious in those circumstances. Are you aware of any warning signs before she stops eg. tail swishing, putting her ears back? I also wonder about the saddle: is it a good fit, is it in good condition, well padded etc? Basically I am trying to figure out if there is something slightly amiss, which doesn't bother unduly in the initial stages, but, having carried the weight of a rider for some time, then becomes a major issue. Try to think of anything at all in the physical realm, that might conceivably be a factor, including things like the condition of her feet, the type of ground you are riding on etc.
  Now to change to a different tack, there is the issue of her deportment. I have no idea how advanced you are as a rider, so please forgive me if I talk about things that are "old hat" to you. She is very young and presumably cannot be very far advanced in her training. Does she hollow her back and come above the bit when you mount her? Also, do you do any trotting when on these rides, and if so, is a rising or sitting trot?
  If you don't follow where I am going in that last paragraph, I will be happy to explain later, but I am going to leave it there for the moment.
  Please let me know your thoughts on what I have just said. I should warn you that, at some stage this site may tell you that you have had too many "follow ups", but it is easy to evade that by posing a "new question".
  So I'll say Slan, and hope to hear back from you.
         Brendan