here the solution.

STEPS:
Go to "fsgame.ltx" and open the file with Notepad.
you immediately notice the repeated lines in the file, read as follows:
"$ App_data_root $ = true | false | C: \ Users \ JAIR2 ~ 1 \ DOCUME ~ 1 \ Stalke ~ 1 \
$ Arch_dir $ = false | false | $ Fs_root $
$ Game_arch_mp $ = false | false | $ Fs_root $ | mp \
$ Arch_dir_levels $ = false | false | $ Fs_root $ | levels \
$ Arch_dir_resources $ = false | false | $ Fs_root $ | You resources \
$ Arch_dir_localization $ = false | false | $ Fs_root $ | localization \
$ Arch_dir_patches $ = false | true | $ Fs_root $ | patches \
$ Game_data $ = false | true | $ Fs_root $ | gamedata \
$ Game_ai $ = true | false | $ Game_data $ | ai\
$ Game_spawn $ = true | false | $ Game_data $ | spawns \
$ Game_levels $ = true | false | $ Game_data $ | levels \
$ Game_meshes $ = true | true | $ Game_data $ | meshes \ | * .ogf; * OMF |. Game Object files
$ Game_anims $ = true | true | $ Game_data $ | anims \ | * .anm; * Even more |. Animation files
$ Game_dm $ = true | true | $ Game_data $ | meshes \ | * .dm | Detail Model files
$ Game_shaders $ = true | true | $ Game_data $ | shaders \
$ Game_sounds $ = true | true | $ Game_data $ | sounds \
$ Game_textures $ = true | true | $ Game_data $ | textures \
$ Game_config $ = true | false | $ Game_data $ | configs \
$ Game_weathers $ = true | false | $ Game_config $ | environment \ weathers
$ Game weather effects $ = true | false | $ Game_config $ | environment \ weather_effects
$ Textures $ = true | true | $ Game_data $ | textures \
$ Level $ = false | false | $ Game_levels $
$ Game_scripts $ = true | false | $ Game_data $ | \ Scripts | * .script | Game script files
$ Logs $ = true | false | $ App_data_root $ | logs \
$ Screenshots $ = true | false | $ App_data_root $ | screenshots \
$ Game_saves $ = true | false | $ App_data_root $ | SavedGames \
$ Downloads $ = false | false | $ App_data_root $ "
Which will be repeated several times, all you have to do is delete repeated lines.



from this thread: https://www.gog.com/forum/stalker_series/fsgameltx_is_corrupted