I have the same problem in one of my older boxes. I never could figure it out... and this was even from a clean install! Other than this quirk, the computer operates just fine, so I never bothered to dig deeper into it.
Soyo SY-7VCA (Via Apollo Pro133A)
Pentium III 933
Generic 512MB PC133 RAM
WD 20GB HDD
Pixelview Geforce FX5200