Hi... I have been tinkering with a number of Linux distros, and have been installing them off of ISOs of the CDs or DVDs. For example, I installed Ubuntu off of a Live CD and then installed the full version from within Ubuntu. Here is the question -- thinking that I would not need the ISOs after installing Ubuntu, I deleted it off of the system and then Linux stopped working. Do I need to keep the ISOs on my computer after installing the system? Thanks.