A Computer Mistake

I am sitting here reading about technological prowess and how most of what one wants to do with a computer can be undone!  This reminded me of a funny episode in my life with computers.  About ten years ago, while learning about some software for genealogical purposes, I discovered that the data files were mucking up the computer.  Since they were saved on disks, I decided to delete the files.  Some of the files were *.tmp files and since it was a DOS based program, I told the computer to delete all the *.tmp files on the hard drive.  Don't do this! You will discover you have to reinstall the boot up files.  Evidently most computers use *.tmp files when booting up.  It is reversible though.  So even if you accidentally delete an important file, you may be able to get it back.