Comment # 5 on bug 1210964 from Doe

The enabling of secure-boot did not help, the problem still occurs.

What's weird: If I choose "boot from harddisk" after choosing USB-Media on
boot,  I see the GRUB2-menu at times, which differs from the "lenovo two
tab"-boot menu (mentioned above) I see normally. Booting from the GRUB2-Menu
works, when available.

Could it be that MicroOS is "made just for UEFI-clients"?

I wonder if the Lenovo default value "Legacy/UEFI: both", "Legacy first" leads
to my problem.

Should I install MicroOS with secure boot and UEFI-only mode again? MicroOS
seems to use GPT, so in my opinion this kicks out Legacy-Clients with only
BIOS, or am I wrong?