Subject: odd problem with a established PPTP VPN connecting a portable using a SPRINT 595U aircard to my home network.

OS's, Equipment, and configurations:

Portable:
Windows XP Home,
A dial-up connectoid to connect to the internet running PPP and TCP/IP, File & Print Share, Client For MS networks for protocols - NO LOCAL FIREWALLS
This connectoid performs flawlessly to the I-net.

A second connectoid to connect to the VPN running PPP and TCP/IP, File & Print Share, Client For MS networks for protocols - NO LOCAL FIREWALLS.
This connectoid WORKS in as much as I CAN browse the web pages served from devices on my network, I can FTP to any of my FTP enabled devices. I am able to ping to machines within my home network.

Network Side:  a M0n0wall APPLIANCE using a Wrap 2e board running the LATEST firmware update.  It has a built-in PPTP VPN server that is enabled and allowing a authenticated user to pass ANY protocols to ANY LAN subnet on my network.
I can successfully ping in both directions.

I CAN click on "My Network Places"-"Entire Network"-"Microsoft Windows Network" and see my workgroup name which is NOT "workgroup". 

HOWEVER, IF I click that workgroup name, expecting to see a list of machines that have MS shares on them. I get a long pause while it scans, then a error message: " XXXX is not accessible. You might not have permission...."

Now if I simply disconnect the Sprint thing, and connect the portage via the LAN jack using the SAME protocols.  I SEE what I expect to see.

WHAT is wrong?   I have spent (No joke) at LEAST 70 hours trying to figure out HOW to setup this thing and this weird problem.  A 2 hour call to Sprint 's level 2 support and ultimately their subject matter expert  ultimately got this reply: " We Don't know"   Which, was a honest answer from them, and WAYYYYY beyond their normal scope.

Thank you all.