HTTP 404.8 ERROR

While working on a recent project involving web services, I started to get HTTP 404.8 errors, which I will discuss in a minute. The odd thing about this error is that it "just started." The project I was working on did not involve any "new" technology that I haven't already used on this box.
My current environment consists of:
- Windows 7 Pro
- Visual Studio 2008 Pro
- IIS 7.5

The HTTP 404.8 ERROR:
- Hidden Namespace. The requested URL is denied becuase the directory is hidden.
What does this mean???

This error is apparently returned when a directory is listed in the RequestFiltering/HiddenSegments of the applicationHost.config file for IIS. The fix for this is partially found at (http://support.microsoft.com/kb/942047). I say partially becuase it is still up to the user to determine which directory is the problem. However, I will still post the fix instructions here, with the caveat that this "might" not be the solution to everyone else's problem with this error.

Steps:
- Open Notepad as an Administrator (right click on Notepad, select "Run as administrator")
- Open the file named "%windir%\System32\inetsrv\config\applicationHost.config.
- Find the element and then the child tag
- Here's the annoying part...at least for me.
- In the section, find the directory that is causing you the problem. For me, it was the "App_Code" directory that had somehow become a problem.

The unanswered question here is: "What caused this error in the first place?" What was I doing when the error was returned? I was trying to use a Web Service instance in a project I was working on. This Web Service instance has been used in multiple projects and this 404.8 had never been returned before. In fact, when I recieved this error, I attemped to see if other Web Services I had recently created returned the same error when I tried to access them through my main application; the same error was in fact returned by all Web Services when accessed through the application, but not when I used the "View in browser" option for each service in VS2008. As frustrating as this was, I was under a serious time crunch to get the application working, and as such I have still not had time to properly research why this error started happening.

I do strongly believe the error to have been caused by some update to either Windows 7, IIS 7.5, or (even less likely) Visual Studio 2008. The update had to have been applied since the middle of February, as that is the last known time that the Web Service in question was successfully used. I may post a question to the forums on these, but it depends on time. Maybe somebody reading this can tell me why this error just "magically appeared" one day.