If you are using CD/DVD discs that are RW, try using R discs. OneCare doesn't seem to like RW discs and usually fails if the disc has been erased.
If that doesn't help, you may have software that is conflicting with OneCare's burning component. If you have DirectCD (Roxio) or InCD (Nero) installed as part of the suite for burning discs, remove them. Packet Writing software usually holds onto the drive, preventing other software from accessing it.
If you need further help in dermining the problem, please contact support.
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
