I have installed xubuntu 12.04 on a 60 G USB 2.0 ext HD. I use this extensively rather than my desktop, which by the way has no trouble booting up the xubuntu from the usb.
I often travel to third world countries as well, and as a result, every so often, I would find myself in a situation where I have no access to the internet, and all the laptops available to me cannot boot from a usb. Generally, I would also not be allowed to make any changes to the laptops.
I have been looking for a solution to this problem.
I ran into PLOP just recently. I copied the PLOP Boot manger iso to a cd, but somehow whenever I try booting the os in the usb via plop on cd, plop hangs.
I have also tried PLOPKEXEC on CD. The results are still unsatisfactory: I can boot a KNOPPIX os from a flash drive with the PLOPKEXEC, but not the XUBUNTU from the USB 2.0 ext HD.
I'd appreciate very much if you can explain these. Even better, I'd appreciate very much if you can somehow help me find a solution to my problem. With or without PLOP.