For the benefit of others, I just ran into the non-round circle thing today myself. I noticed that a couple of 1/4" holes that were cut into my workpiece were... ovals. Subsequent testing showed that the problem was consistent as circles cut into a scrap piece of wood also came out looking like ovals. The problem was that I had recently adjusted the v-wheels for my x-axis and I had adjusted them too tight. They were so tight in fact that when I attempted to move the carriage by hand, it failed to move at all and instead, my X-Carve slid across the bench top. Hmmm. Until I made this adjustment, I could easily move the carriage by hand and so I knew this had to be the problem. Sure enough, I re-adjusted the v-wheels and everything was back to normal--circles were circular and squares were square. So, if your circles aren't perfectly round, check to make sure that your v-wheels aren't too tight.