OK, I have narrowed this down a little bit.
The Problem is caused by my wired PC. I have a wired 2008 R2 server running Hyper-V with 2 VM's running iside it, both also attached to the router (via the host NIC).
I little further digging has shown others on this forum to likewise identify a wired PC to be the cause of a "wireless restart" issue.
http://forums.dlink.com/index.php?topic=5851.0 in particular.
In the linked post, he was able to narrow it down to the Symantec Endpoint Protection firewall, and guess what? I have SEP on this machine as well!
It also occurred to me that the VM's might be somhow confusing things a bit, so I just shut them down and there was no change. Shutting down the entire server immediately changed from having an average of 2 wireless restarts EVERY MNUTE to none in the past hour.
Restarting the server immiately started the wireless restarts as well.
So, my question is, does anyone know what specific changes I could make to SEP to stop this?
BTW - thanks for the IPv6 suggestion - I may try that too if I can't do something with the SEP plan...