I am running LR4 through a macbook pro. My catalog and images are stored on a separate hard drive which is backed up frequently. Recently i had a "catalog is corrupted" notice and choose repair from LR. The repair worked and all seems to be running fine. I did notice that on the disc a new folder was generated called "corrupt catalogs" and a file called "temporary repair previews" was generated as well. I have searched but not really found reference to these items online. I am wondering if this is standard for LR to generate these during a repair, if they are of any use now, and if it is safe to delete them from the disc?