ahhh...this problem
Firstly check for vitamin deficiencies in the dog, giving a supplement like vetzyme will make sure she is not eating her poo because she is lacking vitamins.
Usually that is not the cause though, and so it is probably more a case of just making sure she cant get to anything to eat it, by standing over her like indiesnan suggested. The more she practises the behaviour the more it becomes a habit, so try not to let her practise anymore. Some people find adding pineapple to the food solves the problem, but it sounds like you have already tried that kind of thing.
You could also try keeping her on a long line so she has some freedom to do her stuff, but as soon as she begins to stand up call her into you and away from the temptation, using the line to help bring her into you if necessary.
sportsmonki