Ubuntu 10.10 Internet connection problems...

[DDRtists]

So I'm running a box with Ubuntu 10.10 as a minecraft server, and everything works as intended, minus this one problem I'm having...

Everything works flawlessly for about 2 - 3 hours, then after that, the internet connection just dies. But it still says that it's connected, doesn't throw any errors or anything at all to say somethings wrong. However, when it does this, I can't ping it from other computers, I can't access the internet on that box, and no one can connect to the minecraft server.

However, if I disable and renable the internet connection, everything goes back to normal for another 2 - 3 hours, sometimes a few extra, and then it repeats itself.

I tried leaving it running without the minecraft server, and it still had the same results. Is there a reason for this, or maybe some ideas of stuff to check in to? The network is set up with a NAT Router, DNS Servers, and DHCP, but my router (which is another ubuntu 10.10 box) has a reservation for the server box, so it always gets the same IP. This works for all my other servers no problem, just having problems with this box...

Any help or ideas of what to look in to would be helpful.
I'm running 3 other computers on the same network as that, 2 of them also 10.10, and don't get the same problems with them.

 

[Lyerae]

Are you using wireless? I had issues with Ubuntu randomly disconnecting, though it would happen a lot more frequently.

Also, I think there was a command, ifconfig, that might tell you if the card is connected or not. Try running that and seeing if the computer recognized that it's disconnected or not.

 

[DDRtists]

ifconfig shows the internet information, it's pretty much the ipconfig of ubuntu. The card never claims to be disconnected, and the browser and applications still try to access website information as if it were online but unable to find the domain.
And no, they're all wired connections. I have a wireless access point on the network, but none of the servers have anything to do with that connection.