I have been getting these errors form time to time and do not know what is causing it. It usually happens when I copy a file and rename the copied file to be used as another page in a project. After working on the new file, I try to export the project (either just the files that have changed or all files in the project) and this error is shown in the Export Project dialog.
Any ideas please for how to work around this?
Otherwise, I have been finding the latest version of DHE to be truly excellent and I am using it to build real websites rather than to create files I could use after much further modification by hand as I used to do with older versions. Cheers Julian