Some of my iPhoto events may have been corrupted

I have mainly been using Aperture lately but today I went into iPhoto to look at some pictures I took in Washington DC a couple of years ago.

I went to my Events and noticed that the thumbnail image didn't look right but I double-clicked on it. I was shocked to only see a few photos in there! I used to have nearly 600. I began to panic until I noticed another event called something "Recovered" that shows something like 1,200 photos in it. I looked in there and most of my DC photos are there, but not all. A lot of photos in there don't even show a thumbnail. Just the dashed outline if where a thumbnail would be, and there doesn't appear to be any data in them. No idea what they are

I use Time Machine as well as Carbonite so I'm sure the photos are safe and sound but I need to figure out how to get them back. Mostly I'm worried about what happened!

I did notice that, I guess, I had uploaded all the DC photos to Mobile Me so iPhoto re-downloaded them for me. I hope it's all of them.