I've started trying to get the hang of IK in poser.  I like it, but often switch back and forth.  I don't have any trouble when I do this with legs, but I've noticed arms seem to have all kinds of trouble.  Often I'll go back after working later in the animation to previous key frames and see that the hands/arms are contorted and folded up, no where close to where I had them posed.  Applying a saved pose doesn't seem to help unless I urn IK back on.  Does anyone have a guess as to what I'm doing wrong here?  I'm setting key frames intentionally, but unless I remember to save the pose at each of them the damage is done and I have to repose.

In my opinion you should NOT switch back and forth. IK sets the end of the IK chain as the target and calculates the positioning of the rest of the chain. In Poser the hand is the endpoint.  The translate x,y,z values are only applicable if IK is on.  IK should not change once its set if its a keyframe but the spline interpolation that poser uses by default may be slightly altering the position and giving you a bad pose. You should be able to correct it by fine tuning of the curves and maybe adding some more keyframes to keep the curve very close to your needed values.

I hope the above is clear :(