Error 1155: Not a valid action at the end of a line. - Help Authoring Site
This normally indicated some 'rogue' EasyHelp/Web mark-up in the last cell of a table.
Turn on the show hide button to see if there is anything odd. Sometime the end of cell marker can get changed to a red color. If you spot anything delete the row and re do it.
If you can locate the table that is causing the problem but do not manage to fix it send us an extract containing the table and we can look into it in more detail