Thanks to the wonderful support team at FullControl.net, we are back up with all the missing images. Not sure what happened, but we resolved it with restoring backups of the images. Only 10 minutes lapsed from the time I alerted them to the problem to the time everything was back up.
On a related note, if you need dedicated hosting with great uptime and very responsive hosting, check out FullControl.net. Chuck and the team are the best hosting providers I have worked with, and I have dealt with several.