Router Problem?

I've been having an interesting Network Problem for the last two days.

I run a two computer network through a Linksys four port switch. We share a cable modem for internet access. Everything had been working fine for years until yesterday. Now, only one of the computers can connect to the internet at a time. If you go to the computer that can't access the internet and do an ipconfig /release & renew, it be able to access the internet, but the other computer will no longer be able to.

I can go back and forth between computers and if I do a release and renew before I access the internet, there will be no problem on that computer, but the other computer loses access. When doing a release and renew, neither computer uses that same IP address (one always ends in .100 and the other always ends in .102)

It also seems to switch on its own. If I'm on the internet for 10-15 minutes I will suddenly lose access and the other computer will gain it. A release and renew fixes this.

Interestingly enough, at all times I can access shared files on either computer.

I was thinking I may have a faulty router or that my internet provided (Time Warner Cable) may have come up with a way to prevent multiple computers from using the same connection.

I would start by doing a reset on the linksys and a power cycle on the modem. The modem power cycle is just for good measure, but I bet when you reset the linksys your problem goes away. You will have to restore any settings you had configured on the linksys.