Two months ago, I got a new modem as my old one died a horrible death. I installed it and all that jazz and everything was rosy. The two laptops, PS3, 360 and my iPod all worked nicely. Soon after, however, I noticed that something was a fair bit wrong. Whenever I turn on one of my laptops, my newer one of the two, it cuts out Xbox Live when I'm on my Xbox and boots me offline. I have pushed buttons, changed settings, broke some stuff and it still happens. Since I have my brother using this laptop a lot, it can get very annoying. More annoying since I have started playing MW2 again.

So... any ideas? Help is appreciated, o' course.

Sounds like an IP port conflict.

One or more of the applications you run on the new laptop are using the same ports as the XBox uses to connect to XBox live.

Either that or have you configured a static IP address on these devices? Do the Laptop and XBox have the same IP address?

I'm pretty sure. I tried to set up the static IP but nothing happened. I wasn't sure how to properly set up a static IP so that doesn't help either.

Also, the modem has "custom sevices" for online gaming. I turned on the Xbox Live one, which opened some ports, but that doesn't help.

Definitely leave both devices to pick up automatic IP addresses. Each device's IP address on your home network needs to be unique. You should only really get into static IP's if you know what you're doing (sorry if that sounds condescending).

If the Xbox worked before you connected the new laptop you shouldn't need to do anything on the router / modem. That custom services setting is only really needed if you had problems with Xbox live in the first place.

If you can find out which port number the Xbox is using to connect to Xbox live (I'm not familiar with it), you can then check the applications that you use on the laptop (that connect to the internet, i.e. games) to see if they're using the same port.

Definitely check the IP addresses both devices are using though, set them to auto if they're not.

Sorry to sound like more of an idiot than I already am but how do you set the IP to automatic? (Windows XP) I know how to do it on a Xbox but I have never really looked into that on a laptop.

Right click on your connection > Properties > TCP/IP > Advanced (or properties, something like that) > Obtain IP address automatically