Setup Boot Manager Grayed Out after Win 8.1 Install. I installed Partition Manager 14 Home Win XP 32bit verson under Win XP 32bit. I did "New OS Install" then Setup Boot Manager. I installed Win 8.1 on the new partition. Installed 64 bit Partition Manager 14 Home under Win 8.1 and the "Setup Boot Manager" menu item is grayed out.