I Have yet to see this on the server I admin on, I would be interested if you can find the exact cause, 1 by 1 shut off chunkloaders for ALL bases till you can find the problem base or bases causing the majority of it. Based on the original screen shot I'm assuming it has to be in the nether as those appear to be possibly the only chunks loaded. Then if you can find the chunks associated with using the Most of the Thermal Expansion Handler. Perhaps then narrow down the design for which blocks are using it up.
Ill Keep a eye on this thread for updates.
as EXTREM Last Ditch effort you can uninstale Thermal Expansion (and its addons), start server, stop, Re add TE & Addons, Hope it fixes
Why i state Extrem Last Ditch, as anything thermal expansion will disapear Including WORLD GEN, ores, Machines, ect thats loaded. And who knows what other mayham you might get from removing a core mod like this. BACKUP your worlds if you do attempt.
Iv only attempted this with smaller mods like Portal Gun & Adv genetics in the past, but nothing as big as TE