New Layer color issue, 2012:
http://forums.autodesk.com/t5/AutoCAD-Civil-3D/New-Layer-Creation/m-p/3358577#M171479
Also, for future questions, using a Subject title that relates to the issue you are asking about will go a long ways in having people look at it and respond.
And since you are new here:
It's a good idea to always include the C3D version and which service pack(s) are installed.
If you find a response which answers your question, please be sure to accept the actual post which helped you as the solution. This will help future searchers quickly find answers to their own questions. Thanks!