Hello Satrow...i´ve been out of scene for the Holiday weekend + Three Kings Day, so please excuse my delay. I´m not sure if i explained clearly that changed extensions files i´ve found were located only in the aforementioned pendrive i used. After that -doubting- i tried test operations with another pendrive & ev´rything was ok with the files copied -i did copy, transfer, erase, copy again, etc- so i definitely blamed the fault to the original 16Gb pen i mentioned in my first log... & it was! I did a total data erase, a full surface test & partition again & pendrive recovered all functionality. This could end here
but i´ve gotta say i´m so, so sorry to take up your time with an issue i posted in a hurry that i could have solve, thinking twice before do it.
So i want to apologize for that & let U know i´ve learned for sure how i should proceed next time i use the forum. Lesson learned...Thanks for all !!!