Flash drive unbootable if not fresh format

[Peter Brewster]

Ubuntu operation of 494-1 (and probably earlier unetbootin versions too) will accept a previously used flash drive (i.e., not freshly formatted) and appear to complete normally and without error or caution notice. However the flash drive is not bootable.

After an attempt to boot the screen shows the Boot prompt with a message the next level cannot be found.

Unetbootin should confirm either before starting that a flash drive is freshly formatted (or a DVD is empty) or just before completion that the second level boot records are correct and will be found.

An alternative, perhaps better, is to format the flash drive as the first step - which is OK since the contents will be lost as the drive is written bootable regardless.