Windows Thin PC would not boot from USB drive

ufodisko

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Mar 21, 2013
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I'm using DELL OptiPlex 755.

I installed Windows Thin on a USB drive 16GB following this tutorial , disabled HDD and changed the boot order to USB Drive first.

Still whenever I try to boot from the USB, I get this error.

I tried running /FixMBR and /FixBoot from Windows Installation DVD but it did not fix the problem.

Just yesterday I tried this on another PC from the same model and it worked.

What am I missing here?