Newbie here. My rig gets twisted up when adding IK and a Contraint

Hello everybody,

I'm new to the group, and am learning blender.

I am constructing a rig (armature) for a human in Blender 2.49.  I added IK so that when I move the foot, the leg will follow. I also added a "Locked Track" constraint to the knee so that its movement would be a little more natural. I did clear the rotation (ctrl-N) before doing these two things.

After adding the ik and the contraint, the foot bone (and all its children) started to rotate wildly and I couldn't set it back to its starting position.

What's going on here ?

Thanks for your time and for any help you can provide.

Paul