I finally mangaged to reformat both of my players, erasing all the data unfortunately. I have one set to use on the Mac Pro, the other on my PC with Windows 8. I will not be using them for music since it is tiresome to have to keep loading the same music files over and over just to have to loose it all due to some software issue. Will use just for borrowed audiobooks that I have no financial investment for.
As to some of the above suggestions using front or back ports on the Dell had no effect. I opened the Device manager and deleted all the Clip devices. Then I put the player with the corrupt FAT file on hold, held down the center button for 20 seconds while plugging in the USB cable. Kept holding down the center button until it was finally recognized on the computer. It showed up as a device and I am now able to copy audiobooks onto the player.
Good suggestion to contact Microsoft but quite frankly I am tired of messing around with this. The problems occured on both players on either the Mac or the PC so it might not be a MS issue at all. I would hope SanDisk would persue this with MS.
