There have been many posts on this subject both here and elsewhere. Initially my Sandisk Cruzer 16GB stick worked well, but then it was used for other purposes by my daughter, following this it would not work, the Humax was saying that it needed formatting as FAT 16/32 or ext3. I tried all with no success. Then whilst using "parted" under OpenSuse Linux I noticed that the disk label being used was type "loop". I vaguely remembered that before it had been using a dos format, a quick look at the options showed that there was an msdos option so I tried that. I now have a working usb stick again. I hope that this information is helpful to others.