Hello, I have a problem with my USB flash drive: LEXAR JDE256-04-500. WHen i bought it, i has 250 mb like described on the box, but now I only have 70mb available. If i check the drive's properties, it says that it has 250 mb total and 180 mb used while I have nothing in the drive !! This situation deteoriates each time I format the drive and now i have only 70mb left... Help!