Glad to hear my suggestion helped and we've established this has nothing to do with x10's hosting - but I came across another wrinkle yesterday that may be applicable to others experiencing this. In this case, thumbnails were visible in the media library for older images, not for newly uploaded images and not at all in the post editor insert image dialog box. Obviously new thumbnails weren't getting generated and something was hiding them in the insert media box.
Running the plug in I linked to above in this case didn't work. I isolated the cause which was an older version of the wpecommerce plug in. Updating that, and regenerating thumbnails fixed the media problem.
So my guess is something changed in WP 3.8 which either by itself or when combined with an outdated plug in can mess up the image meta data functionality. First I'd try to identify if it's a plug in. And if not try the rebuild image meta data plug in.