It depends on the encoding in which the subtitle file was saved.
You can check by opening the file in a text editor (a text editor like EmEditor http://www.EmEditor.com
will mostly detect the correct code page and display it somewhere on the screen.
For most latin based languages the cp1252
(West European Latin) codepage will work fine (this is also the default in PSM).
For Japanese you would use sjis
It could be that your subtitle file uses only a few special characters that are not correctly encoded or that are not available in the selected codepage.
If you can not find the correct codepage and the rest of the text displays ok it might be easier to open the subtitle file in a text editor and replace all the instances of the problematic text, the three dots (these will be displayed as one character), with three actual dots (...)
see also http://en.wikipedia.org/wiki/Code_pages