Re: Can't Live Boot from SanDisk USB
Your description is not clear as to whether you installed Ubuntu directly to the Sandisks, or burnt the Iso to it.
I did a direct install. I do not know if this will apply to your Sandisk Cruzer flash drives, after what you have done to them.
I have 12.10 booting, & running, OK on an 8Gb Sandisk with a 1GB ntfs first partition - so Windows will recognize it, and for mutual access Switch files - 6Gb for Ubuntu and 1Gb as a swap file. I created the Switch partition in Windows, and then created and formatted the rest in Gparted, without difficulty..
I originally installed 12.04 on it, directly from a LiveCd, later upgrading to 12.10.
It has its own Grub so I can boot to it, either from its own Grub Menu, after selecting it in the Bios boot menu, or from the HDD Grub menu. Thus it is independent and mobile.
My Bios does not permit making an USB the default primary boot device, as it sees an USB as a hard drive, and I have to run down the drop down menu to select it.
The only problem I have had was from shortage of space after multiple kernel updates; I had to delete some old kernels to make room to install Ubuntu Tweak to clear out the crud.
"Better Solutions may bring Worsened Problems": After Lao Tse, b. circa 405BC. a contemporary of Confucius, who died circa 600BC.
They did things differently in those days, apparently!!