Before I installed Ubuntu my Thinkpad edge bios allowed me to specify boot devices, their order etc. Now it only says Ubuntu in the boot device list. I am thinking this has to do something with UEFI but I am not sure what to do exactly. I tried every sensible combination of BIOS settings but nothing helps. Maybe someone had a similar issue.
This is clearly a firmware (what manufacturers and most people call a "BIOS," although it's not) bug. I recommend you go to your manufacturer's site and look for an update.
If that fails, my only suggestion is to use a third-party boot manager that will provide its own way to boot an external medium. My own rEFInd should do this, although in some cases you'll need to hit the Esc key to re-scan for bootable devices after it's booted.
Edit: It occurred to me after making the original post that disabling any "fast startup" type options in the firmware might also resolve the problem. Sometimes these options prevent the firmware from detecting a removable USB flash drive, so if such an option was accidentally enabled, it could cause the symptoms you're seeing.
