My notebook (HP dv6-6100tx) can't use GRUB2. It always hangs. I have reported this issue to GNU. Their engineer and I find out that a memory area which is declared as available by BIOS's E820 can't be clobbered, otherwise BIOS's INT13h will hang. My BIOS's version is F.1B. I have installed a 4GB and a 8GB memory on notebook. There's more technical detail in my bug report for GRUB2.