It seems that when a player disconnects from an IndustrialCraft SMP server while on a chunk that contains a terraformer that is running it causes the game server to become unresponsive. It fails to respond to console commands or connecting players, and players already connected are unable to interact with the environment.
No error is reported.
Version: IndustrialCraft 7.20
Minecraft 1.6.6
Steps to reproduce:
1. Create a terraformer and insert a chiller blueprint
2. Supply terraformer with power
3. As the last player near the terraformer, disconnect from the server.