Steve-
I did not make these changes that are being ascribed to me, and I hope no one else is reverting them. It certainly seems strange that what I add to pages now seems to be deleted automatically, and I am being labeled the deleter. Is HAL 9000 acting up again?
These are your sysop powers at work :-). Sysop have the ability to go into any user's contribution list, including their own, and "roll back" any user's edit of an article, so long as it is the most recent edit to that article (which the "top" marker refers to).
You have accidentally rolled back your own contribution to a previous revision. Don't worry, the rollback is only a shortcut to editing the previous version and saving it, so no data has been lost. Just edit the previous version and save it.
Regards,
Erik