Odd image thumbnail behavior

[flalaw]

I've been experiencing some weird behavior with thumbnails in Lion. I've got a folder full of picture files. Some of these pictures need to be rotated 90 degrees. Sometimes when I do a rotation in preview the change in orientation is reflected in the folder thumbnails, but sometimes it isn't. Secondly, random pictures have no thumbnail at all. Luckily, whenever I've got an image that isn't displaying thumbnails properly I can select the picture, hit get info, select the image icon (sometimes a thumbnail of the picture if one exists) in the upper left hand corner next to the file name, hit delete, and then the problem is fixed and a properly oriented thumbnail appears. But I don't want to go through this step and was wondering if there was some way to prevent this or at least an easier fix than going through all my pictures one by one. Thanks!

 

[flalaw]

Oddly enough this is mainly happing to older groups of pictures on my computer.