I recently had a problem with sorting of chars. I have some Eastern Europe chars. like ????? and they didnt sort like I would like to in views. "?" would come at the end of the list after "Z" and it should be after "D" so I found the solution and the problem.
Problem is collation of tables in mysql database and solution is changing it. They were all set to "utf8_general_ci" so I just change node table "node" because I was sorting by title and I did this.
alter table node convert to character set utf8 collate utf8_unicode_cichanged it to Unicode, and now they are sorted perfectly.