Various causes: There are very many causes, from congestive heart failure, to lymphedema, to venous insufficiency, blood clots, pregnancy, a various other causes, including serious and not-so-serious causes.
I have a Sony DVP ns55p blu-ray player with a usb port in the front. The player requires that the usb flash device (thumb drive) be formatted in FAT32in order to recognize it.
Press the white slider on the side of the Cruzer Micro USB flash drive and slide along the track to reveal the retractable USB plug. Plug the flash drive into any available USB port on your computer. The computer will detect the USB device and install the device automatically.