I have an Unique Star USB flash drive (512 MB capacity) that has been having problem since I purchased it. I can store and retrieve data on it for the first 175 MB or so without error, but after I exceeded a certain capacity, the data become corrupt and I cannot retrieve the data once I copied them to the disk. The files would simply disappear, or if the file is listed in the directory, the file would be empty (zero size). I always use the device manager on the system tray to stop the disk before pulling it out to avoid corrupting data. And it's not a hardware issue because I got another disk (with the same capacity and the same manufacturer) with the same issue. Has anyone else experienced the same problem? I appreciate any input. Thanks in advance.