O.K, the boost sensor in the box is actually a litle tiny diaphragm, if it is damaged it is usually due to the box being exposed to vacuum witch will actually rip the diaphragm, where is your box located on the sled? it should not be under the hood due to the constant temperature fluctuation witch will cause moisture to form in the box, mine is located on the handlebar riser, just Velcrod to the side, some guys actually put it inside a zip lock bag to keep it out of the elements. Make sure that the boost sens line is not pinched or kinked in any way. Where does the boost sens line from the box ty into the sled, it has to be in a spot where it does not see any vacuum at all, some of the older kits where tied into the vacuum-T set up on the throttle bodies, this wont work at all due to the constant vacuum the box is exposed to at idle, on my sled it ties into the inter-cooler on the top left hand side if you were sitting on the sled, I have also heard of guys who will bump the throttle during the sleds warm up cycle, this can also cause problems, have you checked your ground connection ? if you unplug the boost sens line and start the sled it will re-set the box, shut the sled off, plug the line back in and try it, you can also unplug the box completely and plug the sled back in stock and start it, run for a minute or so and plug your box back in. On my box the edges are sealed with black silicone, Alpine themselves did that to keep the moisture out. How old is your sled and what turbo are you running ? Was the first box you had the exact same problem or a different one ? The way you explained that the box re-sets itself almost makes me think you have a bad connection somewhere, or moisture got in the box itself.
Let me know what you come up with.