I've installed Lubuntu 14.04 on an AsRock 775 VM 800 with a Pentium 4. It often boots to the Lubuntu splash screen for a few seconds and then displays what appears to be a black screen. After a while the monitor reports that there is no video signal. At this point the hard drive light flashes occasionally. The video does not respond to the keyboard and mouse. There is no response to power cycling the monitor (off then on). I even switched to PS/2 keyboard and PS/2 mouse to eliminate USB initialization problems but the problem happens regardless of whether the input devices are USB or PS/2.
This board is described as having the following video support: Integrated UniChrome Pro 3D Graphics. The BIOS seems to have a setting to specify AGP or PCI. Neither setting makes a difference and perhaps the setting applies to plug-in video cards, of which none are present.
I have swapped monitors, keyboards, mice, and installed a voltage regulator. The problem persists.
Very seldom does the Lubuntu login screen appear, but if it does, the unit is functional and was tested with Skype and Firefox, so I know the OS is present and common applications work.
How do I resolve this black screen problem?