Metro outages blamed on computer glitch

As Ian noted in comments Wednesday, the afternoon outages that afflicted the whole metro system except the yellow line have been blamed on a computer problem.

Used to be “a computer problem” was an all-purpose general handwave, but now most of us use computers all the time and would enjoy knowing more. Did someone delete a bunch of files by mistake or move them to the wrong directory? Did someone trip over a cable? Disk crash? Coffee displacement crisis??