For the CMYK color scheme, color specifications must be enclosed in quotation marks. For all other color schemes, the quotes are optional. You can freely intermix color-naming schemes in your programs ...

Perfect for use in ‘all-over’ schemes in both contemporary and traditional settings, these delightful neutral hues work ...

The issue seems to arise out of some incompatibilities with color rendering Win32 APIs under specific conditions. The problem seems to be most common with the white color. Here's how Microsoft ...