A friend of mine wanted to add additional RAM and a decent video card to his system which I agreed to do for him. I am not a hardware guru but I have installed RAM on several systems as well as a couple of video cards before; straight forward stuff. After installing the new components, I booted up the system and installed the video card drivers. Computer was rebooted and everything was working fine; extra RAM present & video card working without conflicts. I then decided to plug in a 19" monitor. When I booted up, I recieved an "Operating System Not Found" message. Tried booting a few more times and same message. When I went into the BIOS, the Primary Master & Slave both showed "None" and the Secondary Master & Slave showed the cd-rom and cd-writer (which is correct). All cables were checked and were plugged in properly. Looks like I may be footing a repair bill and was wondering if anyone had an educated guess as to what this problem could be related to.