Psychopy data file (psydat) corrupted

Hi everybody,
I use v2020.2.4 on Windows 10. My psydat files are corrupted (they are written with weird symbols; see attached JPG).

An error message (that may or not be connected to this issue?) appears on the command window:
“pygame 1.9.6
Hello from the pygame community. Contribute - pygame wiki
WARNING:matplotlib.font_manager:findfont: Font family [’’] not found. Falling back to DejaVu Sans.”

Any help is welcome.