Is this a small server? If so, try breaking and replacing all the energy links. I would use MCEdit unless you load the world in between the removing and re-adding.
Remove .techniclauncher/tekkit/mods/IC2NuclearControl_client_v1.1.10b.zip and add the file from the post above labeled client. The .techniclauncher folder is in whatever the .minecraft is on your OS.
This may have been the worst bug report I have ever heard. Please post the error log from techniclauncher/logs/launcher_0.log. Also, what server are you joining? Do you have a firewall? Are you on the right version of tekkit? Do they have other mods? All the information you have is what you need to put.