The most common cause of individual [dead] comments on an otherwise not-banned account is double posting. If you accidentally submit the same comment twice, the

The most common cause of individual [dead] comments on an otherwise not-banned account is double posting. If you accidentally submit the same comment twice, the second one is killed. Since both show as live on your screen, when you delete one of the duplicates, you may delete the one that's live to everyone else, while leaving the one that's dead to everyone else.