I run 10.6 and recently installed 10.9 as a dual-boot. Both work well and I boot into the smaller 10.9 partition by default. I needed to install Windows XP for some old applications so I started boot camp, except now it says "The Startup Disk cannot be partitioned or restored to a single partition. The startup disk must be formatted as a single Mac OS Extended (Journaled) volume or already partitioned by Boot Camp Assistant for installing Windows." Boot Camp worked fine before Mavericks was released and I only had a single Snow Leopard partition. Both the 10.6 and 10.9 BCA say that. Switching the startup disc doesn't change anything. My startup 'disc' (Mavericks) is a single HFS+ volume, as is Snow Leopard. What does this mean? What am I missing?