problem with loading sketch with archlinux

Hi all, i've a problem with the loading of the sketch in arduino, when i try to load the code, the idle say me "done" and the led on the arduino (the led that starts to blink when the code is loaded) starts to blink, but effectively the code isn't loaded, that is the arduino continue to executes the old program. I'm sure there isn't error of programming also because i tried with the code example present in the arduino ide, I'm using archlinux, when i use windows i haven't this problem and all works correctly, the problem isn't the permission file because i given it to my user, so can anyone help me ? Thanks to everyone.

Try holding the RESET button, when IDE says UPLOADING SKETCH or white text appear, release the button. If it fails, try reflashing the bootloader.