Hello,
I had one problem with "Unity 4.3.x Package" of pathfinding,
maybe this helps somehow:
After importing actions I got playmaker editor freezes.
Found a "solution" by deleting one action after another and came up the "NavMesh Find Closest Edge" action - deleted it and had no problems after that. I'm not using it so its ok for me:)
Hope you get the cure soon;)
And download the pack for Unity 4 only.