FMC Freeze and not just on NGX

Well, after several years of using the NGX, I started having issues. Today when I parked on the gate and started preparing for my next flight, both of my FMCs have become totally unresponsive, left one shoving landing ref page but with some missing numbers, and the right one (which I haven't used) showed the first init page it does when its powered on. None of the buttons on fmcs seamed to do anything, both in vc and in 2d popup. All of the other displays worked just fine. This issue has occured multiple times over the last month or so, and, even stranger, exact same issue occured on my Majestic dash8q400, fmc frozen and displays working.