I'm assuming the issue is that some exploit in the last year has resulted in the UEFI being revoked. Can I ignore this warning, turn off secure boot, update Ubuntu, and then turn it back on? Or do I ...

So, I was working on my Dell D600 last night when it completely froze on me. Forcing a power down by holding the power key and then trying to boot up again yielded nothing but a flashing CAPS lock key ...