You're probably using a combination of Body and Hip to move and rotate the model. Any movement or rotation of the model using Body is ignored by Poser when you save the pose. But 'ah!', you'll say, 'if I move or rotate using the hip, the IK makes the model's legs go all squiffy'. Indeed .. you need to turn IK off when rotating or moving the model.

Those who specialise in making poses would usually recommend that you don't use IK at any stage, but use the dials instead (more control and you avoid accidental mesh-mashing). When saving poses, always have IK turned off. If it's on when you save a pose you practically double the size of the pose file. And if a pose saved with IK turned on is applied to a model which has IK turned off, you can get some very odd happenings.