On a Windows 8 computer if you try to burn files to disc, when another operation is already in process, The second operation will not complete successfully, but you may instead get the error:
There was an error burning this disc. the disc might no longer be usable.
This error occurs because the first copy session is still in progress. If you select "Burn to disc" again, Windows will attempt to burn files to the same drive again in a different session. This is not a supported scenario.
You should wait for the first file copy operation to get over, before starting the next one, says KB2748977.
Fix: Disc Burning operation to DVD-R Dual Layer disc fails in Windows 7 Explorer may also interest you.