On certain audio cds I wish to play on my computer, I get a message box that comes up and says that the device is not ready and/or the device is locked. But like 90% of the time, the cds I want to play work fine. And the other 10% of the time, I try to play those cds on my mother's computer and they play just fine. What is the cause of this and how do I fix it? I obviously know that the cds can be read on computers, just not mine.