Re: Unable to edit newsletter HTML (page locking up)
These suggestions worked for me:
Open the editing page, do not scroll !
Zoom out the view until you can see the button that you need to edit that is causing problems. You must zoom out the page, you won't have time to scroll down.
Change your layout of the email and when you click save you need to be quick at clicking on the edit button you need to fix the problem. If you catch it in time the pop-up will show. It may take a minute or two for all the text to display, but it should if you give it time. You can delete it then save and should be good to go.