Does the drive work with other burning software? If so, have you recently installed any burning software that may be blocking OneCare from using it?
If the drive cannot be accessed using other burning software, then it has probably failed. If it works and you can't get OneCare to use it, please contact support for help.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
~ Microsoft MVP Windows Live ~ Windows Live OneCare| Live Mesh|MS Security Essentials Forums Moderator ~