The system started becoming slow, I dont know exactly why. Maybe because I had so much pictures and music in it. I tried factory reset, it solved for a couple weeks, but then same behaviour again. After that I decided to flash a newer firmware (samsung original), went to sammobile got the newest one and flashed it. Brand new GS4 feel? Not so fast... This damn ORIGINAL firmware was more buggy than my previous one! (Yes I did flash it correctly) Sometimes I experienced totally random reboots, and another rebooting whenever I tried to open the camera app (it froze then the system rebooted) pretty frustrating for me... And then something happened with my micro sd card, i dont know wth why, but my sd card got a bug so that I cant delete any file no matter what, I've tried formatting from the phone, on my PC, on other peoples phones, but no matter how many times I tried to delete something the data was still there, again pretty ****ing frustrating. Thank you samsung!