Strange things happen when you use "other" colors as layer attribute.
1. Create a new layer, give it a name and choose some custom color like #AA00AA.
2. Draw something in that layer just to visualize the behaviour.
3. Open the attributes of that layer again and OOPS, the color is said to be black/white even though your objects are still nicely pink.
4. Now change some other attribute, like line width, and click ok and BAM your layer is black/white again.
Apart from that there is some other error I can't always reproduce. But sometimes when returning from the color picker into the main Layer Attribute Window, the layer's name is completely erased.