needs to be changed. Boot into safe mode and set the video resolution to the default settings that the monitor likes: 1440 x 900 @ 60Hz . In Googleing for that response, this thread is talking about the Acer monitors giving this message.
When you set the resolution, be sure to check the refresh rate to 60 Hz as that seems to be the stumbling block for the Acer.
I recently decided to upgrade from a Geforce 6150SE to a Geforce 9400GT. After uninstalling the old one and installing the new one, I tried to reboot. Everything seemed to load fine, but instead of giving me the login screen, it just said "Input Not Supported". I've tried uninstalling the 9400 and switching back to the 6150, but it still gives the same message when I try to boot up. It only works in Safe Mode or with no drivers installed. Everything was working fine up until I tried to upgrade.
My monitor is an LCD Acer AL1916W, 1440 x 900 @ 60Hz and it connects through VGA. I've tried changing the refresh rate settings, but the only option I get is "Use Hardware Default Setting".
One more thing, I'm using Windows Vista Home Premium 32-bit, if that helps.