I have faced this problem for months. With a Windows 7 laptop computer on a 64 bit processor, I have experienced persistent issues reading content on a Sandisk Cruzer 16 GB USB drive. On some occasions I was lucky to access my files within minutes however on a number of occasions I have been frustrated ejecting it then loading it again. After reading this chain of messages I uninstalled Samsung Kies then attempted to read files on my USB drive but it did not work. I even changed the drive letter for the USB drive to S from E, in vain. After uninstalling Sony Play Memories software which I had installed some months back, the problem appears to have been fixed. All my USB drives with a capacity of 8 GB or 16 GB made by Sandisk get recognized quickly and the files are read with no problem. I don’t think I could have guessed that this media software from Sony interferes with the driver for the USB drive from Sandisk. I must thank this person who discovered it. A stroke of genius, perhaps ?