Nathan,
From your experiment, i read that if RB1100 receive packet, do reboot.
Maybe it’s related to virtual interface module or port flapping?
normis said in the other thread, dated may 25, 2012, http://forum.mikrotik.com/t/metarouter-stability-on-rb800-rb1100-rb1100ah/50384/1
stated metarouter issue on PPC fix with latest bios version,
5.17 maybe ? or 5.18rc1 ?
can you check this out ?
thank you.