Monitor only has 16 bits/colors

Compaq Presario 5000, Monitor MV540, Windows ME, Display driver NVIDIA Vanta LT (COMPAQ). I have restored the computer back to factory level. I am only running the base PC, no new programs, no printer etc. But I only have 16 color. The system tells me it is aware of a problem with the display. It says the device is either not present or not working properly or does not have all drivers installed (code 24). I downloaded a sofpaq (SP 14540) from compaq drivers, but this did not correct the problem.