Is it me or does that not fix the problem of the machine re-starting in the first place ?
The article states what the meaning of the error is and why it shows up... (Please note that it specifically points to the fact that the machine was restarted on purpose, not a spurious issue. Something is purposely causing the machines to restart and since the third machine is NOT rebooting it is not the electrical circuit they are connected to...
Since there are 2 machines exhibiting this behavior it is very doubtful that it is a hardware issue as the cause would have to effect both machines at the same time... VERY doubtful. (Besides, as already stated this particular error means that a piece of software purposely caused the reboot so it can't be hardware.)
So my suggestion is take a good long look at the software being run on these boxes and more to the point.. WHO has rights to them as I would guess you have an INDIVIDUAL that is rebooting these boxes... Or a program that is doing it on it's own...
Either way, it isn't hardware it is a software and rights issue. (Rights because someone that shouldn't be is rebooting your boxes)