Here is a great thread on how a person reported fixing a problem 500.19 error NetBios command limit and using a UNC based content architecture.

http://forums.iis.net/p/1165964/1937935.aspx

http://download.microsoft.com/download/7/4/f/74fe970d-4a7d-4034-9f5d-02572567e7f7/24_CHAPTER_11_Troubleshooting_IIS_6.0.doc

http://support.microsoft.com/kb/813776

Check out the UNC tag regarding others that have great information.

http://weblogs.asp.net/steveschofield/archive/tags/UNC/default.aspx

Steve Schofield
Microsoft MVP – IIS