Bug number one: a corrupted Ubuntu installer

The symptom

the Ubuntu 12.04 alternate installer fails when installing the base system, telling you that the disk is corrupt. You'll get an error message along the lines of "problem reading data from the CDROM".

The problem

Unetbootin/7zip have known bugs with long file names/file paths. These have been open for a couple of years, so don't expect them to be fixed soon.

The solution

Use Ubuntu's startup disk creator instead. You can either run it from the launcher or as usb-creator-gtk from a console.

Bug number two: your DBAN USB key won't boot.

The symptom

When you try to boot from your DBAN USB key you get the boot menu, but attempting to boot any of the entries fails with the message "Could not find ramdisk image:/ubninit".

The problem

Unetbootin doesn't configure syslinux.cfg properly.

The solution

Edit syslinux.cfg, replacing all occurrences of "ubninit" with "ISOLINUX.BIN" and the one occurrence of "ubnkern" with "DBAN.BZI". It's case sensitive, so make sure it's all uppercase.

Bonus DBAN/Unetbootin tip

Unetbootin creates a default boot option for DBAN that includes the --autonuke flag. This means your DBAN key is especially dangerous – if you boot off the key, either by accident or design, it'll wipe all disks without any human intervention. Avoid this by removing the --autonuke option from the section marked label unetbootindefault while you've got syslinux.cfg open.