Is the display shutting off and the unit still running, or does the whole unit shut off? If it is the laptop shutting down, then it is a thermal issue. There is something about the GPS unit you are using that the cpu does not like, maybe a driver, maybe the power draw by the GPS, and dealing with the GPS unit, the cpu reaches the thermal protection limit and shuts itself down. When you disable the GPS, the laptop is still running because it has not reached the thermal limit of the cpu. It has a chance to cool a bit before you enable the GPS again.
The CF-29's use passive cooling, no moving parts, and so the thermal interface between the cpu and the heat sink/case is important. It is probably using the original, installed at the factory, thermal pads. If it was my unit, I would open it up and replace the thermal pads, the one for the cpu and the one for the video chip as well as the chipset pads. If you do not have access to thermal pads, use a bit of quality thermal paste on the existing pads.
The CF-29's have been around for awhile now. The thermal interface, if it is original, has dried out and is now more of an insulator for the heatsink/case. Any sudden shutdown problems on these units are probably heat related.
Hope that helps.
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