I have Windows 7 Home Premium and have been using it on my Del 720 XPS with no issues for a month now. Today, while browsing, the screen flickered and the resolution dropped to 1024x768 and my sound stopped working. I have installed, un-installed, and re-installed all of the drivers from both the manufacturer, from microsoft, and from 3rd parties. I have unseated and reseated the video and sound cards. Nothing works. Windows 7 recognizes my display driver (nVidia 7900), my monitor (ViewSonic vx2235) and my sound card, but I still have no sound and 1024x768. I also cannot get the computer into safe mode - there is no video signal to my monitor until the main desktop is displayed. Finally, no viruses or spyware - I've scanned several times.