I have several Windows XP workstation that will not register returning and
error code of 2. I've logged the error, details shown here:

Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Entering
ZenLiteTree::ZenLiteTree()
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Entering
ZenLiteTree::ZenLiteTree()
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- ConnType = 2
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Leaving
GenerateImportDoc
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Entering
HTTPUtil::SendMessage
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- HTTP server =
172.16.64.1
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Loaded novhttp.dll
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- About to create an
HTTP connection.
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- hSession = 0
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Leaving
HTTPUtil::SendMessage, returning -3
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Entering
HTTPUtil::SendMessage
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Aborting
SendMessage. Server address is empty.
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Entering
Registrar::Import
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Import failed.
Error: 2
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Leaving
Registrar::Register, returning 2
Friday, March 31, 2006 08:49:54 -- ZENWSREGRegister -- Leaving
ZENWSREGRegister, returning 2

The workstations that fail can ping/resolve zenwsimport (via HOSTS file,
and also tried specifying in the registry). I have other Windows XP
workstations that do register successfully (same container/context), so
that would imply that my ZfD server components and policies are in good
order.

Can anyone comment specifically on the errors noted above:

ZENWSREGRegister -- Loaded novhttp.dll
ZENWSREGRegister -- About to create an HTTP connection.
ZENWSREGRegister -- hSession = 0
ZENWSREGRegister -- Leaving HTTPUtil::SendMessage, returning -3

and

ZENWSREGRegister -- Entering HTTPUtil::SendMessage
ZENWSREGRegister -- Aborting SendMessage. Server address is empty.
ZENWSREGRegister -- Entering Registrar::Import
ZENWSREGRegister -- Import failed. Error: 2

Seems like this is the core of the problem, but can't determine what the
cause might be.