first of all: well done! The new release ist greate (even though i also liked the 2.2 - and still also use this version).
I have started a drawing in the stable release (2.2). Afterwards i changed it with the new release (first 3.0 rc3 - then 3.0 rc4, when i noticed the problem).
I cannot tell when it really started - but now the colors of all layers, which used to be black, are set to "custom" and appear to be something between brown and red. If i change the colors again to "black", then everything is ok. I save the file and when i open it again, the color settings are "custom" again...
I don't know how the attach a file... but i can send it via email, if you want.
P.S.: operating System: Windows XP