It appears that either a new layer (or layers) was (or were) created
or a layer (or layers) was (or were) purged. Layers can be created in
startup in ACAD200xDOC.lsp, ACAD.lsp (with ACADLSPASDOC set to 1), or
a routine than one of them loads at startup. Because of the
volatility of layer states, I find that they really don't work very
well except for the immediate drawing session. There is always
somebody in the crowd that loves to create layers for whatever or for
no reason at all, and you can't get them to stop. Because of that,
LMAN is something that if you want to use it, fine, go ahead, but
after somebody else has been in the drawing, you'll have to fix your
layer states.
Bill DeShawn
http://my.sterling.net/~bdeshawn