When you 'add' your pictures to Starter Edition, the program notes where the file is, and creates a reference thumbnail representation of the picture for you, so that you can work with a large collection of files in different places on your hard drive. If you move or delete any of your pictures, that will result in outdated references to your files in Starter Edition. That is what is meant by 'missing file'; the file has been moved, deleted, or renamed.
The way to make it stop is to delete the picture of your file (with the red icon) in Starter Edition, because it is no longer able to locate the original moved/deleted/renamed file.
The other way to fix it is to move the file back to wherever the program 'thinks' the original file is.