I purchased a PowerColor HD 5770 video card so I could get a third monitor working. I have two widescreen monitors, one attached via HDMI and the other attached via DVI. My third monitor is attached from DisplayPort to VGA (using a passive connector like this one)
The third monitor is a 19" Hyundai L90D. I was unable to find any Windows 7 (or Vista for that matter) drivers for the monitor, so it's stuck with "Generic Non-PNP Monitor". It's native resolution is 1280 x 1024. Randomly Windows will boot up in the correct native res, but sometimes it boots up in 640 x 480 res. When it does boot up into 640 x 480 res, the screen resolution slider is stuck and I cannot slide it back to 1280 x 1024.
I cannot find a pattern for when or why it will do this, I've tried rebooting five or six times in a row at times to get it to boot into native res, but this doesn't always work.