Both my new drives came today, a dvd rom, and a rewriter. Have installed into case and reconnected everything. When I started up the pc it took ages to get onto the main screen, didn't really take much notice of that, but when I tried to play a cd, nothing happened. In device manager optical drives are no longer listed. When the pc came on a second time it beeped and I quickly saw that something is not compatible, but I did see that both green lights came on, on both drives. What has happened, and how do I correct this?