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.
Instructions. Install the software that came with the Bluetooth dongle. If your Bluetooth adapter came with a CD or DVD disc, insert it into your optical drive. Wait for the autorun to start and click Install to start installing the drivers. Insert the Bluetooth adapter into an open USB slot.