Recently I got the following error while importing an usual text file obtained by copy/paste from a web page. The file contains some combinations of symbols that cause the error. The combination (in hex) looks like

(first 3 symbols are BOM, Byte Order Mark). In a text editor the file looks like a symbol

The code

Import[StringJoin[ NotebookDirectory[], "ErrorText.txt"], "Text"]

causes the error "An error of unspecified nature occurred." in Messages box. But next operator

StringLength[%]

returns 2 as string length. The text file is available here (only 9 bytes in length)