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Is it the thinkpad that won't stay powered On? if so, then it may have a damaged AC Adapter, or a worn-out battery also.
If it is the Vupoint that isn't staying powered On, then it may simply have a setting that allows it to time-out and power-down when timed-out, if unused for a sufficient period of time.
How old is the Vupoint in question? measured from its date of purchase.
Do you have another PC or computer to test the Vupoint on?
If the Vupoint scanner won't stay On, then (if it is not the kind that is powered only through the USB cable) try turning it On with no USB cable attached from it to any other device, and see if that relieves (or perfectly duplicates, perhaps) the condition.
Let me know, please. Thanks.