I can't get Vista RC1 (clean installation in a new VM) to successfully boot with High acceleration set (regardless of VTx setting). Reducing speed to normal works fine. - default "new VM" installed via parallels unattended install (slick!) - Mac Pro 2.66 - 2GB RAM The installation reaches a race condition, either while booting, or while running a processor-intensive app (usually while booting). The resulting crash tends to corrupt anything caught running.