When attempting to open HTML Help (.chm) files the operation may fail and you receive an error message similar to the following:
Cannot open the file C:\FolderName\??????\filename.chm.
This issue can occur if you attempt to open HTML Help files (.chm) from a folder location on your local computer or on a networked computer that contains GB 18030 or Unicode characters in the path.
To work around this issue, you must save the files to a location that does not contain GB 18030 or Unicode characters, or you can replace the GB 18030 or Unicode characters with ANSI characters in the path name.
HTML Help supports ANSI characters but does not support Unicode or GB 18030 characters. Therefore, HTML Help cannot open help files (.chms) that are in paths that contain GB 18030 or Unicode characters.