I am on Verizon FIOS and have had some odd problems recently as well. 1 or 2 accounts run fine, go above that all accounts spike, even ones on other computers that the kids are on. Sometimes I will have 2 running and the kids each have 1 for a total of 4, no issues. I pop 1 more everyone spikes. Or nobody is playing and i pop 3, start ok but in 2-3 minutes all 3 spike to over 4k. Shut one off, other 2 drop to normal.

Other times we can have all 7 in our household running, 4 on mine 2 kids and 1 for wife and all are 80-100,ms, normal.

I will also have issues where only one of my accounts is having issues while the rest are normal. I usually have to restart that client. Sometimes it fixes it sometimes to goes to another client. It is always with 3+ accounts on my box

When there are issues it seems to involve my vista64 machine having more then 2 accounts up. It is not consistent as to the exact cause and I am only boxing occasionally right now so it is not that large of an issue for me. If I still have issues when i get moving again I will dig further.