In a nutshell - got a new Samsung ultra laptop, don't like the way the disk is structured and lack of facility for creating recovery disks so wiped the 500gb hard drive which is formatted to gpt, repartitioned to give me a 50gb partition for win8, 50gb partition for win7 and the rest reserved for data. Installed win8 from my own install disk, shoved stacks of apps on - all so far, so good. Booted from external optical drive to install win7 to its partition, all went well to first reboot - then: starts booting win8 goes into endless loop saying "your pc ran into a problem, . . . . starting repair. Looks like the gpt disk has got corrupted with an mbr - no problem I thought, nip into bios, boot from optical drive and run repair or, if desperate complete reformat and reinstall from there. And there lies the problem - absolutely will not enter bios on boot - the only boot device it seems to be willing to look at is a gpt disk with an mbr and I can see no way of getting into the bios. All shops are closed now and tomorrow I may get an external case for the 500gb hard drive and repair/reformat by plugging into usb on another pc but any ideas in the meantime? I'm not often stuck when you just can't get access to the damn thing. . .!