Because newdotnet gets into your connection settings, removing it can also damage your ability to connect to the internet.
This plugin will bind itself to the windows socket layer to intercept all DNS requests from your machine. Due to this, you should not delete this file (as it will prevent your computer from accessing the internet/any network). Instead, you should look online for a removal tool or instructions on removing it safely.
I wouldn't go looking for this dll to see if it resolves the problem, firstly it is spyware and secondly where would you put it and then you would have to register it I believe.
However as your XP set-up doesn't connect to the internet I don't know if this might present itself in other ways.
This has been used in the past to restore connections lost when newdotnet is removed, even though you don't normally connect with XP.
Lost Internet Connection - To recover you internet connection, try downloading and running WinsockXPfix:
http://www.snapfiles.com/get/winsockxpfix.htmlNEWDOTNET - Check out this topic
http://forum.avast.com/index.php?topic=21608.0No needs to do all of this.
For XP SP2, try Windows Start button, Run - type 'netsh winsock reset' without the quotes - this may be enough to fix the issue.