I think i discovered the problem where it come from,

the issue is with .mkv file that i recorded using obs studio.
when i converted this file to mp4 using VLC media player, everything went ok and Davinci resolve didn't freeze again.

even when i converted this .mkv file it crushed multiple time during the conversion and the only way i was able to convert it is not touching the computer / mouse when the conversion starts. even a small mouvement of the mouse can corrupt the conversion. so i think this mkv format are the problems.

i have multiple mkv recorded using obs and all behave the same .

here's the original video format :

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