Copying the old iTunes application back probably won't do you any good, Mark. The reason is that the corrupt system files will still be in place, as they are stored in other locations on your system. Before you do that, I think you should try all of the steps which I outlined before, or simply restore your system from the older Time Machine backup with iTunes 10.4.0 and then simply upgrade again. Robin> > Click on the link below to go to our homepage. > http://www.icanworkthisthing.com > > Manage your subscription by using the web interface on the link below. > //www.freelists.org/list/macvoiceover > > Users can subscribe to this list by sending email to > macvoiceover-request@xxxxxxxxxxxxx > with 'subscribe' in the Subject field OR by logging into the Web > interface at //www.freelists.org/list/macvoiceover >