This may not help but how about not checking the automatic update option? Just keep the installer offline and update once the system is up and running.
I wonder if this is some UEFI or other Windows boot remnant interfering - just a guess. Check the first link that @zabadabadoo posted - #3 & #4 show you how to disable Windows interference.
If you get past that, some suggestions on partitioning: Partitioning during installation