I'm trying to update a Macbook Pro with 10.6.3. The latest using Software Update does not complete downloading. After 475 Mb an error message says it can't connect to the update server. I tried incrementally updating to 10.6.4. It downloads, starts to install, and just before finshing the install gives a "software error" message and quits. Is this a known issue, and how can I get around it?