Easy to recreate. Simply place any mekanism pipe (mechanical, logistical transporter, etc) down and cover it with nether brick. Leave the chunk, come back and then break the brick. I think it may be with loading the graphics on the mek pipes maybe? They do load 6 times every tick I think. Not sure though, I'm certainly no expert. Just doing my duty as a server owner to report bugs! :)

Thanks guys!

P.S. Sorry no crash log, I've got my server hosted on a weird site and I'm not even sure how to get to my files... lol.

What version did this occur in?