We cannot get our remote and local sites synchronized for the first time. We have a huge site and we get out or memory errors or the synch just doesn't work. Any solutions or insights?

Our site has 9,000+ HTML files and accompanying images, pdfs, etc. When we try to synch the remote to the local for the first time, it just will not happen. Every once in a while someone gets lucky, but for the most part, we either get an "out of memory" error or the synch just doesn't work, and it doesn't tell us anything. It just stops responding. HELP!