Hi,
Unfortunately I know very little about what the display bars mean during a shutdown, but perhaps I can help you remove your handlebars so you can inspect your connectors, etc.
Removal of the handlebars is pretty simple. Near the middle of the CSB where the lower section of the handlebar connects to the base of the Segway, you should see a hex nut that holds the handlebar to the base. Loosen this nut with a hex wrench (I believe 5 mm) and once loose, carefully pull up on the lower shaft of the handlebars until you feel it pulling up and out. Once the handlebars are free from the base, you can un-clip the connectors and examine those.
Removal of the upper part of the handlebars will require you to remove the rubber bezel around the display and key port, first. Carefully peel the rubber up starting from the key port side, and work your way over to the display side as you pull it off. If you're like me and can't really get it peeled off any more than about half way, carefully bend/fold it up until you can see another hex nut in the middle of the top of the handlebars. Unscrew this nut with a hex wrench (I can't recall if this is also 5 mm or smaller) until the top of the handlebars becomes loose. Then to remove them completely, you will need to twist the top part of the handlebars about a half-turn, if I recall, until you feel them pop off the rest of the handlebar shaft.
I'm sure several others have explained the process in far better clarity than I, so if that's the case, a brief search of this forum RE: Handlebar Removal should get you some other results.
I also have a crazy idea as to what may be causing the shutdowns... Have you recently adjusted the handlebar height up a little bit? When I got my gently used i167, it would safety shutdown if the handlebars were raised above a certain height, and also sometimes just by hitting bumps along the road. This could explain why the shutdowns only happen while you are riding and not when the Segway is sitting in balance mode - even small bumps and vibrations while riding could possibly be causing it. Maybe try lowering the bars to a lower position (as low as possible, commensurate with safety of course), take it for a glide and see if the shutdowns continue. If they don't, it's possible you have a variation of the same problem my i167 used to have. Let me know if the lower handlebar position solves the problem, and I'll give you a detailed description of how I fixed it on my machine (you can also read a bit about what I did on this thread:
http://forums.segwaychat.org/showthread.php?t=33327)
Hope some of that helps.