BACKGROUND:
I installed GitStack 1.4.1 on my file server (Windows 2008 R2) and on my client PC I installed 1.7.10.msysgit.1 and TortoiseGit 1.7.8.0 (Windows 7 32-bit). I followed the instructions (https://gitstack.com/import-an-existing-repository/) to import an existing repository. I also created a few empty repositories. Finally, I created a few users and groups and assigned permission to the repositories to the users and groups.

PROBLEM:
When I attempt to access the repositories on the file server, I get an error similar to:

git clone http://serverName/repo.git
Cloning into 'repo'...
error: Couldn't resolve proxy '(null)' while access http://serverName/repo.git/info/refs
fatal: HTTP request failed

I expected to be prompted for the user ID and password. I even tried:

git clone http://userId:password@serverName/repo.git
Cloning into 'repo'...
error: Couldn't resolve proxy '(null)' while access http://userId:password@serverName/repo.git/info/refs
fatal: HTTP request failed

If I access the repository on the server via a shared directory it works:

On the file server:

net share git=e:\GitStack\repositories

On the client:

net use g: \\serverName\git
md t
cd t
git clone g:\repo.git
Cloning into 'repo'...
done.

At this point, I have a repo directory that contains a clone of the repo.git repository.

QUESTION:
Why is http: access to the repositories not working?