Thanks for the input. I realize that this is a DoubleTwist forum, not Itunes. That said, I've done a full delete and re-install of Itunes several times. Each time, Itunes has worked properly, that is until I try to sync through Doubletwist.
I've updated the registery as well, with the same outcome.
The issue is a bit outside my area of expertise,admittedly, and I have concerns that Apple support will say it's a Microsoft/DoubleTwist issue, Microsoft will say it's an Apple/DoubleTwist issue, and DoubleTwist will say it's an Apple/Microsoft issue.
No matter the outcome, I will be the loser, I'm afraid.
I'll keep you posted, but I've already been down the path with the solution you recommended, to no avail.