First guess: you have a driver problem (on the Samsung).

See if the problem repeats on another computer, preferably not the same model; i.e., load the stick up again and see if you can read it elsewhere. If the problem follows the stick, get rid of it. If it doesn't, your problem is most likely the USB drivers in WIN7, or the hardware itself on your computer. Try other USB devices in the same port and see what happens.