MPC nepoužívam - neporadím, preto skús toto:

Q: Subtitles show weird symbols
A:

This may happen if the subtitle language requires a different code page than the language of your Windows locale settings. You can solve it by adjusting the code page settings.

Media Player Classic options -> Subtitles -> Default Style -> Click on "Default (1)" and change it to the correct setting.

DirectVobSub options -> Main tab -> Text Settings -> Click on "Arial" -> Click on "Default (1)" and change it to the correct setting.

This problem may also occur if you have Logitech Gaming Software installed. Remove or disabling that software will solve the problem.