I have a question posted in the Networking section of this forum "Connectivity issues" which might explain, reloading xp would be a last resort & I am just gathering information just in case.
What Does it Do?
NewDotNet is a browser hijacker and can update itself without any input from you. Anything that modifies your windows HOSTS file is a hijacker and we don't want it! The "purpose" of this is to add support for additional domains like .AGENT .INC .LOVE .SHOP .SPORT. We suggest you remove this.
If you are prepared to format the hard drive. This may actually be the best way to go.