IIS 7.5 site 20,000 UNC virdirs via NetApp Filer Results in 500.19 NetBios Command limit reached errors thread
If you run Windows Server 2008 R2 and NetApp appliance. Definitely a thread to bookmark.
http://forums.iis.net/p/1172082/1958863.aspx
Check out the UNC tag of forum posts
http://weblogs.asp.net/steveschofield/archive/tags/UNC/default.aspx
Cheers,
Steve Schofield
Microsoft MVP - IIS