If my machine did this from the beginning, I'd make the vendor fix it.
I will share that a few things have been noted that causes this and there are more. Here's the short list:
1. Drivers for motherboard and video are not installed by the person who installed the OS. Tip: Microsoft doesn't do drivers.
2. The power supply browned out during boot and the video card dropped out at the wrong time. XP can respond by falling back to a generic VGA driver.
The color quality listed in "Display Properties" will drop from 32 Bits to 8 Bits on it's own. I could be on the internet and open MS-Word and the screen color quality changes. The upper tool bar looks smeared. When I go to the Control Panel/Display/Display Properties the setting has changed to 8 bits. Been this way from the beginning???