frankie to clear things up, when u have an error like that it usally means ur RAM, so you may want a RAM upgrade soon. and the kind of files on there, no not ever single file, only files and programs that you are using on your computer, and when you shutdown your computer your RAM is erased(thats a good thing) cuz if it didnt erase you would never be able to run other programs, but plz tell us your OS and amount of RAM, to find this information, goto your control panel and goto the icon that says "System" click on that and you'll get a window that tells your basic computer specs, the last spec at the bottom of that window says how much RAM you have so if it says "256,000KB" that means you have 256MB of RAM, but plz give us the info so in case you do need a RAM upgrade when can direct you to the correct RAM to get and well tell you how to install it.