Comment 2 for bug 319817

I was experiencing a similar issue except the installer reverted to the location selection step. I was using the Kubuntu Alpha4 live CD. I also could not mount my extended partitions after exiting the installer. It told me the device does not exist. After rebooting the partitions could be read normally. I think this bug may be related to bug 324987 - "Kernel *loses* partitions at partitioning stage; installer fails".