I have purchased 2 USB Drives from 2 different sources and both were Knockoffs.

It seems what is happening is the older 1 GB drives are being virtually expanded to allow more data to be written to them, when in fact they cannot accomodate the data.  The result is complete file corruption.  Steer clear of any Data Traveler drives shipped from China/ Asia as they are most assuredly bogus.  There is a test that can be performed to determine an authentic drive.  this test was created by another Ebay member and works very well.  Shop carefully.