I am stumped by this and so is every tech support person so far!! I have 2 video cards installed with 2 monitor ports on each, and I am running 3 monitors. All were were working fine for about 3 months. Now the second slot on both cards does not work. The video cards both test fine. I have uninstalled and resinstalled drivers, done software restore etc and nothing changes. I have Windows XP home. When windows start the second monitor shows the startup, but as soon as windows actually starts it goes blank. When I look in the display settings (either through the ATI utitlity or windows) the second monitor is not enabled. If I enable it the screen will refresh and still the show the monitor as not enabled. The power supply is sufficient for the cards. Everyones solution is to reformat my hard drive and reinstall windows - which I will only do as a last resort, and I am afraid the problem will happen again. Any suggestions would be most welcome. Thank you all.