Ubuntu – Booting and installing from USB

I've been trying to install ubuntu (server edition, 13.04 i386) through a USB pen drive, and so far I've miserably failed. This is on a lenovo x230, with USB-* options all up there in the boot order, as well as UEFI / secureboot support disabled (as it seems it messes with most linux distro). So far I've tried this (on my old ubuntu 10.04, and sometimes, purely out of boredom, on win 7) :

• The native usb-creator-gtk proving to be useless (i.e. crashed), I've instead opted with unetbootin. Invariably, it only gives me a "Boot error" message when plugged in, and nothing more. I've been careful to always format the usb drive first (FAT), through the graphical tool or some other console tool (msdostk… mtkdos… something along those lines) and shoot a "sync" as well as a "eject /dev/sdX" afterwards.

• Copying directly the iso : using "cat", "cp" or "dd" directly into the pen drive. Most of the time, it would simply not boot. A few days ago I was trying my hand at installing debian, and this is the only thing I've tried that actually worked, was to copy directly the netinstall image on the pen drive. Unfortunately I've had problems with that installation which are outside the scope of this post.

• As I was writing this, I was also trying out some other tool, Universal USB Installer (win 7, with the same iso as before). And lo and behold, the god forsaken pen drive did boot. Only problem is it's in rescue mode (maybe ubuntu is recognizing the existing debian installation?) and even then, is insisting on mount the cd-rom drive (which is inexistent). Great.

So at this point I'm thinking it might have something to do with the pen drive itself (although it is able to boot, albeit once in a goddamn blue moon) or the laptop settings.