I've checked out quite a bit of audio from my local library and put it in Windows Media Player. I've never had difficulty in burning any of it on cd's until this evening when I got an error notice saying that the system is unable to find the file specified. This same canned response to every attempt I make--"System unable to find file specified". I've tried a number of different files, even many that I've successfully burned before, but the player will no longer allow me to copy music on a cd. What on earth can I do?