While I rarely move the cables around there is a known problem that has us do the following.
1. Power off the cable modem.
2. Move the ethernet cables.
3. Power up the cable modem, wait, then power up the router.
Well discussed why so I'll stop here.
Bob
I connect my cable into the router that's for my xbox live and it works and I look around XBL and then after disconnect it and play my games, then the next I go and connect it and the internet is not working on the computer and I can't connect to XBL, I give and try today and it's still the same. What is the problem?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic