Thank you for reaching out to the Constant Contact Community!
I am sorry to hear you are having some issues editing that email. I want to ensure that you can finish this one up and get it sent out!
First, in this case I am going to suggest trying to edit that campaign on a different web browser. If that fixes your issues then you may just need to close all of the windows on the original browser and restart. If you continue to have issues once you have restarted your browser then I suggest clearing your cache as a last resort. Click Here for more information on that process.
I sure do hope that this helps but please let us know if you have additional questions or if this issue persists.
Thanks and have a great day!