It's a puzzle to me why if you have the encoding / character set option set correctly you are not getting subtitles correctly displayed.
Where are you playing the files from? I guess if it's a network share then the share could be setup with charset options that are incorrectly transmitting the special characters in the srt file. You could test this by playing the same file from a USB drive formatted as FAT32.
I don't think it's a problem with Q10 setup, but to be sure you always have the option of a firmware reinstall. So resetting everything to factory state. There will be a new firmware next week so I advise waiting, but current 1.0.3 firmwares are linked to from here: http://www.futeko.com/newforum/index.php?topic=711.0