Something is keeping the prefs from being written properly. What background utilities and programs do you run?
We're running Macafee 9.1, Lotus notes 8,5,3 fp 3, Universal Type 3.3.1, Office 2011 Sp2. Nothing out of the ordinary.
Users are standard users on the machines.
Just becasue it isn't out of the ordinary doesn't mean it isn't a problem.
Not being a fan of Extenisis type managers in general, I don't keep track of the versions, but 3.31 sounds a little early for CS5 comapatibility, so try disabling or removing the auto-activation plugin. I also have nothing good to say about MacAfee and have never heard anyone else say they run it on a Mac.
As a Windows user I don't keep close watch on the known bad apples (pun inteneded) on the Mac platform, but I remember that MacKeeper causes all sorts of trouble in ID, too.