The problem is probably because PARENT_URL is obsolete and was removed a while ago from Zope, quite a while ago, I think in the 1.10.x releases.

Hmmm. PARENT_URL was used in the method for creating a new NTUserFolder. I guess Ive not created a new one since the release of Zope 2.0. This problem has provided enough motivation for me to release a new version, fixing this and adding several new things: http://www.zope.org/Members/htrd/NTUserFolder