Re: Dual booting ubuntu 32- and 64-bit, 64-bit version stuck at initramfs
When running 2 systems like that, where did you put grub for each system? One might step on the other if they both think they control grub in the same mbr.
When I ran both 32 and 64-bit systems from the same internal drive some time ago, I put the grub for one in the mbr and for the other on its primary partition. That worked fine, I just had to boot the one that controlled the mbr and run sudo update-grub on that if the other one did kernel updates. They did not share a /home.
When I installed both 64-bit Lubuntu and Ubuntu 12.04 on SD for my tablet PC with separate common /home partition, I put grub for Lubuntu in mbr of SD, but Ubuntu would not let me put grub on its partition, so I did not install any grub for Ubuntu. Those both work fine with common /home partition. I just have to do sudo update-grub from Lubuntu for Ubuntu kernel updates.
i5 650 3.2 GHz, 8 GB, nvidia GTX 550 Ti 32" 1080p | i7-4700, 8 GB, Intel HD 4600/nvidia GTX 765M 15.6" 1080p | etc.