The latest versions of Ad-Aware will not remove New(Dot)Net any more, as it's 'no longer considered spyware'.
First go to Start/run, and type Msconfig. Go to the startup tab, uncheck New.Net application, and click OK.
Now reboot, and the program will not load again with Windows, preventing the recurrence of your error message.
Now go to Software add/remove, and remove New.Net application there.
Don't attempt to remove the dll manually, because that may cause the loss of your internet connectivity.
If uninstalling doesn't get rid of the dll (it happens), try this:
First, you will need to locate the New.net ".dll" file that is on the computer. Do this by doing a search for "newdot*.*".
The file will be located in your "Winnt" or "Windows" folder (depending on what version of Windows you are running). Once found, make note of
the actual filename which should look something like this:
Close the Find or Search window then...
Type in the following line:
For Windows NT users:
For Windows 95/98 users:
You should then see a small window asking if you want to uninstall the New.net application. Click Yes. Once this is done, restart your computer. This should keep the .dll from loading up at startup of your computer.
More info: http://www.cexx.org/newnet.htm