I was on a call with a level 2 tech from Xplorenet for quite a while last night trying to straighten some things out. One of the things that came up was that we're running out of numbers to use for IP addresses so Microsoft has decided to expand the address length. Where before it was 4 groups of numbers, they've expanded it to 6 now. If you look in your network properties you'll see that there's a 'version 4' and a 'version 6'.
The tech said that for the next couple of years you might as well shut off version 6 since the IP's haven't expanded to 6 parts just yet, but will in a couple of years. He said that keeping version 6 running now will just bog down performance.
Not sure if I've got the whole story right, but I know I'm pretty close.
Has anyone else heard of this?