Strange SonicWALL VPN client disconnect issue

I have a small customer that has a SonicWALL TZ180 and we are using the GVC client to connect remotely to the office for RDP sessions.  I have 5 active users and 4 of them have no problem at all.  One user cannot use his laptop from home at all.  I have checked and configured the DPD settings in accordance with SonicWALL recommendations in relation to the Failed to decrypt buffer error notice.  That removed that issue but there is another one going on that I cannot seem to resolve.

I can connect to the firewall and authenticate properly, I get an IP address no problem, and then I can even RDP to any machine in the network.  After about 5 minutes the RDP session freezes and I get the network broken icon in the right upper corner the RDP session darkens and then seems to reset.  Sometimes it drops you out sometimes it allows you to continue.  I have noticed that on occasion the connection seems to reapply for a DHCP address, sometimes the GVC app shows it reconnecting, sometimes not.  There is a desktop that we tested from and it works properly.

I do not appear to be having an issue with other networking from this machine but I'm not sure.

I have tried the same machine from a different ISP and different network equipment and it seemed fine.

Specifics on the environment:
ISP = RCN
Wireless router = DLink (MIMO) not sure of the model
Laptop = IBM Thinkpad R50
Intel Wireless card
Intel NIC

This is the only user on RCN by the way.


Steps taken so far:

Tried the laptop wireless and wired, same issue.
Reloaded the GVC
Reloaded the drivers for the wireless
Tried a new wireless card
Tried a different wireless AP (Linksys Wireless AP only)

I tried to reset the DPD but that only resulted in the Decrypt message to return.  Is it possible to remove all the networking pieces from XP then reinstall, would that even help?  Anyone have any suggestions?  I do not have access to this env all the time, it is the owners house and he only has someone there certain days.