I am facing following problem

Hello,





A few pen drives are not readable on my system, while some others are doing just fine.
not sure why, but when inserted first it show auto play option but then when I try to choose open files option it hangs up. finally I see the pen drive in my computer h: drive but not showing it's size or content. I tried to see device manager, it's not showing up there in any of the usb controllers. What is the problem and solution if any? Thanks in Advance