Can you figure out what the image is that is missing? Is it a thumbnail for a picture or for an album (I can't tell which exactly). It could be there was an error in uploading or importing that image that the data is stored in the database and the actual image is not there (or not readable), or it could possibly be that the image is too large for your server's settings for time limits or temporary memory limits.
I think it's referencing a missing thumbnail (a picture that was moved or deleted). Go to the Admin -> Manage section, click the little pencil and paper next to the album in question, change the pulldown thumbnail to Plogger Default, and save your results. I think (hope) that should clear things up for you.