I've done two upgrades to Quickbooks 2008 from 2006. Both times, the QB file was on the network. In order to upgrade the file - you have to install QB 2008 on a machine and open then file. When I opened the file when it was located on the network, it gave me an error about permissions each time. Then I had to restore the QB file from backup. In short, in order to upgrade the file - I had to bring the file down local and open it there and then copy it back up to the network.