We have an iMac DV that just started acting up. During boot the monitor is fine--displays colors and good resolution. But once the OS is loaded the screen is sort of black & white. I've check the contrast and brightness, changed resolutions and color depth, nothing has worked. It is almost like a reverse negative image. No colors, just black and white. Is this a hardware issue or software setting? Again, the monitor is fine when OS X is loading. This iMac has been working fine for years. It was working fine when my kids were playing a game, then the next day the display went crazy. Could my kids have pressed a few buttons or something? This is a G3 CRT iMac DV running Panther.