Hi!
The problem is well known; if you have an installed openSUSE 11.4, you can use it's own USB-installer, 12.1 I don't know.
There are many different UNetbootins - I always use PartedMagic/ UNetbootin, the best of them,
but with openSuse it might be a problem.
Alternative:
With Therminal command "dd". I did it in the past with success, but at the moment i can't say how to proceed.
I'll search in the net and post again.
alfredo
Edit:
http://forums.linuxmint.com/viewtopi...28#p366328/url
chapter 17 and 19 (Mint!)