unable to access old files after downloading new version 4.4

Hi guys,

I've just downloaded a new version of MUSESCORE and suddenly I can't access old files in my computer. The programme can't read them anymore. No idea what happened. The problem seems to partially with Czech symbols (like "č" or "ř") since it does not decode them, but the problem is probably deeper.

Can you help me solve it ASAP?

Best,
T. Jajtner