Sorry my question wasn't clear Ponch... I'll try to clarify. In the nLite'd file directory used to create my ISO image, I see the following: One file named Last Session. One file named Last Session_U Four files named Last Session with several numbers (205407.xx-xx.xx.xx) These are configuration files that are saved on the CD as part of the ISO image. Every time I make changes to the image files using nlite, it creates a new Last Session file. I was trying to understand the meaning of the different files (Last Session, Last Session_U) so I could delete unnecessary files but still maintain a copy of the most current Last Session configuration on the CD. It sounds like I can safely delete all of them, so you answered the most important part of my question, but it would still be nice to know what the Last Session and Last Session_U files are for and if deleting them would affect or corrupt the last saved configuration information saved on the CD. Thanks for your help.....!