Welcome. I'm not sure what exactly caused it or how to prevent it, but I should be able to help you get the world back. Backup the world and use MCEdit to remove the block from this location: 'Block location: World: (-112,111,162)' That is the block causing problems and should allow you back into the world.
P.S. Since you teleported I wonder if the block is on you. If it is on you then you must backup and delete, or if possible MCEdit, your player.dat or username.dat on the server. If you delete your player.dat you might loose your Thaumcraft research, as I'm not sure where it saves that info, that is why I had you back it up. The items you loose can be refunded with NEI.
