Hi again,
Just today I have upgraded my Fedora 9 IPA-server to the latest Fedora version, namely Fedora 10.
As reckless can one be.. just upgrade the system (with all of its db4 libraries), while the ipa instance is still running, increasing the risk of corrupting the (live) berkeley databases that are the back-end of the ldap instances.
I managed to fix the problems I encountered.. read on to read about my investigation and how I solved the problem, it might be of use if you happen to have the same symptoms . . .