First connection from Vista client to SQL Server 2005 times out

This is very odd.

I have a VB6 application. I have fixed it up to play nice with Vista,
and embedded a manifest (contents at the end of this post) into the
exe.

When I try to connect to the SQl Server 2005 server from a Vista
client, I get a timeout on the first try. My app asks to verify the db
settings (server name, db name, etc.), and I do that, retry and it
connects fine. It does this every time. It only fails to connect on
the first try, it always connects on the second try.

The app has an optional second database it can connect to, and it does
the same thing. Times out on the first connection attempt, click the
retry connection button and it connects just fine.

But here's the weird part. If I recompile the app, and do not embed a
manifest, it works fine with no other changes. So the manifest is
cause this for some reason.

Here's what the connect string looks like:

Provider=SQLOLEDB;Server=10.0.0.167;UID=;PWD=;DATABASE=thedb;Trusted_connection=yes;Persist
Security Info=True

It doesn't matter if I use a trusted connection and "NT
authentication" or supply a user name/password for SQL Server
authentication. It doesn't matter if I put the server name or the IP
address. It always times out on the first connection and works on the
second connection, but only if there is a manifest embedded (otherwise
it connects fine on the first try).

(And yes, I'm aware the Persist Security Info is a no no -- the app
was copying the connect string around in a couple of places, and I'm
in the process of cleaning that up so this is temporary).

Here's what the manifest looks like:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1"
manifestVersion="1.0">
<trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
<security>
<requestedPrivileges>
<requestedExecutionLevel level="asinvoker"/>
</requestedPrivileges>
</security>
</trustInfo>
</assembly>

In this case, I am logged in from a domain user ID with domain
administrator permissions. Haven't even started trying to test it as a
mortal user yet.

Any suggestions?

.