Default Videos are currupted in internel memory !

Few days ago i founded a problem that some hd (about 720p) videos that i recieved by using 'shareit' (a file transfer tool using wifi) are currupted or not playing videos ..

some videos are plays but after a few minute played it will closes and says the video cannot playable..

in video player all the recieved videos have the running time is shown as 00:00
..
And a video recorded by scr screen recorder has the same time running 00:00 ..
Also my hd games (with heavy data file) are lagging some times later that i have been started playing..

My question is,

Is this an internel memory problem and any solution for this?

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