Okay...first of all, I have that Comcast Triple Play thing...internet, phone and cable. We have the Comcast modem...and then I bought a wireless router (so I can use the laptop and desktop at once). Normally, when I'm home, I'll have my laptop downstairs so my daughter can play Nickelodeon games online, or something like that and never had any problems with using both at the same time...but, ever since I came home from California, it seems like you can only use one at a time...and, normally, it's the desktop (the one that's NOT using the wireless capabilities of my router). Now, I finally brought my laptop up to my room, where my modem/router and desktop are at, and plugged it into another port on the router, taking out the wireless portion. Now, I was doing fine with using both computers at the same time. Oh...and, normally, what happens when I try using the both of them at the same time is that the modem with basically reset itself, kicking both computers offline. If you've seen me playing the last couple of days, you'll see me disconnect a few times a day and reconnect a couple minutes later...that's my modem resetting. Now...when I had the laptop plugged directly into the router, it seemed to work fine...both computers were connected to the internet, and the speeds seemed fine....but, then I was playing CSS on my desktop, turned around to show my wife that the laptop was working fine, internet-wise...and, BOOM! Modem resets.
I know this sounds kind of confusing, but that's the best way I can think of to describe this problem. Anyone have any ideas??

EDIT: Before anyone says anything about a bad laptop or anything, as I'm typing on this computer, my laptop is downloading a movie off the wireless connection (unsecured) from my neighbors...no problems on this computer, or the laptop. So it's definitely a problem with either my router or my modem.

The modem itself is re-setting? As in, power cycling?

If it's not power cycling and instead it just drops the network on a schedule (I mean, every 2 hours, every 8 hours, etc), it could be something else.

In my case, I got tired of sleuthing my setup and ended up just buying a shiny new router, and everything works just like that. But along the way I learned some stuff.

Yeah....resetting. Out-of-the-blue, it will drop the connection and reconnect without me touching anything. Normally, when I lose connection to the internet, I'll get pissed off and do the Windows Network "Diagnose" thing...and, by the time it tells me that it can't find anything wrong, the internet will be working again.

If the cable modem really resets it'll most likely do a diagnostic light show thing when that happens -- and if it does that I'd just say have Comcast or whoever replace it if you lease it. That should never happen, regardless of whether you plugged a laptop into it or a french fry.

Yeah...since I have off today, and my wife and I are heading out that way anyways, we're just going to take the modem into Comcast's office and have them give us another one.

I had this issue when I was still living with my parents and they used Comcast. They ended up having to replace the modem.

Wow...Comcast blows F*CKING nuts. We called the 800 number, for Comcast tech support...they told us to bring the modem into the Comcast office, 30 mins away, to be replaced...and they also said that they'd send a technician out to our house to make sure it's not internal wiring in the house that's screwed up. So, my wife went out there...and, as she was gone, the technician came (an hour earlier than they said he'd be here), and said that there's nothing he can be sure of unless the modem was here and plugged in, and that if it was the modem, he could have replaced it right then and there. So, the guy leaves (after he said that there's nothing wrong with the wiring that he could see), and, five minutes later, my wife comes home and said that the office wouldn't replace the modem. So, we called Comcast again, and now they say that they can't get anyone out here until tomorrow now....so, yeah...a wasted F*CKING day trying to get working internet....

Wow. That sucks C*CK dood.

Alright...so, the Comcast guy came back today, swapped out a couple things and brought the modem back into their dB range that it's supposed to be in (mine was higher than it should have been). The modem, itself, is working fine...so, the guy leaves and I play CS...tits...works great. Tried using my laptop on the wireless portion of my router...no luck. So, I'm thinking my router is bad now. I took it out of the equation and have my desktop plugged directly into the modem for now.
Next question: What brand of wireless router is better, Lynksys or Netgear. I had a Netgear, and had no problems with it up until now....but, I'm just a regular guy...I don't know much about computers and networking. Also, what's the pricerange for a decent router? I'm not made of money (two kids and pretty-much living paycheck to paycheck), so I can't spend more than $100, I would say.

Linksys, its Cisco it rocks.

I bought a cheap 40 dollar one for use when I go to my grandmothers for the weekend and it's just so F*CKING awesome, solid performance.

What Taz said. You shouldnt have to spend more than 60 bucks for a perfectly good wireless router with 5 or so physical ports on it.