A couple of clarifications...
1. Hong, the issue is when deploying when disconnected from the web. In that case GlassFish is trying to retrieve the DTD over the network.
2. Richard, GlassFish should always use the local copies of the DTDs and schemas that it knows about, which should be all the ones in the lib/dtds and lib/schemas directories. You shouldn't have to do anything to enable that. As Hong mentioned, if a descriptor refers to the the DTD's system or public ID incorrectly (if the name is slightly misspelled, for example) then that can cause what you are seeing because GlassFish will not recognize the DTD as a locally-stored one and will try to retrieve it over the network. Of course, if the ID was misspelled then it should not exist at the network address, so I'd think you would have seen an error about that.
[Message sent by forum member 'tjquinn' ]
http://forums.java.net/jive/thread.jspa?messageID=374103