I used to that too - I forget the values, but it was a "mocha" colour/theme I copied from somewhere.I made my HUD color changes in the GraphicsConfigurationOverride.xml file.
They've never changed.
HTH
GUIColour>
<Default>
<LocalisationName>Standard</LocalisationName>
<MatrixRed> 1, 0, 0 </MatrixRed>
<MatrixGreen> 0, 1, 0 </MatrixGreen>
<MatrixBlue> 0, 0, .03 </MatrixBlue>
</Default>
</GUIColour>