IP address resetingFollow

Are you behind a router, or directly connected to a modem?

It sounds like some sort of odd proxy error.

Proxy servers are 'middleman' servers between your computer and the Internet. You can route your Internet connection through a proxy to mask your IP address, and some businesses do it to share a server across many computers.
There are also malware programs called 'dialers' that will route your computer through a proxy, in order to track your usage information. If you've had your browser hijacked recently, popups that come out of nowhere, any reason to believe that you might have a dialer on your system, check out Spybot Search & Destroy. This program should find and remove anything that might be diverting you through a proxy.

Otherwise it could be a router error, or bad settings on your router. If set all IP addresses manually across your network, and make them static, it should fix the problem.
Since it just came out of nowhere though, my guess is that there's a malware program that's messing with you.