Try not using Layer 0 for your Xref's and most of all DO NOT LOCK IT. CadMep relay's on it. The same holds true for Defpoints. The only reason to use Layer 0 is to make blocks other than that try not to use it.
Make a Layer called XREF's for your xref or if you want it at the top of your list of layer names use the Under score in layer name _Xref
I don't believe you can do today's job with yesterday's methods and be in business tomorrow.
