We have an application we just upgraded from .NET 1.1 to .NET 3.5 (it is set to use 3.5 but we're really only using 2.0 features right now).
It is working just fine on a dozen machines but there is a single machine where the application will not run.
The error is "Error creating the Web Proxy specified in the 'system.net/defaultProxy' configuration section.
This is almost a clean install of XP Professional SP3 and I have installed, uninstalled, and reinstalled .NET 3.5 SP1 already -- no success. I read something about click once / guest accounts but we don't use click once and the guest account is disabled, I'm logged in as the administrator.
The main login form of the application pops up...but the login action itself tries to make a soap call to our server and this is when the exception occurs.
The inner exception is "Feature requires windows 2000 or later" but this is XP Pro SP3! It is a legit, cleanly installed copy with all of the priority updates installed from windows update.
Since it is working everywhere else in the office it must be a simple configuration of this machine but since this is nearly a clean install of XP (only added acrobat, firefox, AVG, and WinDbg) I'm not sure what the setting could be. A lot of our machines have acrobat, firefox, and AVG -- I only added WinDbg to see if it could help me any. I've tried disabling the windows firewall but that didn't help.