Thanks to Michele, who discovered one of those rare Unicode UTF-16 text files, found that DelightEd couldn’t make any sense of it, and reported the bug. It’s now fixed, in a new release.

DelightEd version 2.0b4 now opens UTF-8 (standard), UTF-16 and UTF-32 text files, and is available from here: DelightEd20b4
from Downloads above, from its Product Page, and through its auto-update mechanism.