Errors Not Viewable Despite Proper Configuration

I'm having the classic (dare I say typical?) error on the ASP.NET production server, which tells me that I can't view errors. Below the error displayed below, are things I've already tried. In IIS Manager (6.0), the application is located under one of the web sites in "Web Sites". It is indeed a web application, as opposed to a virtual directory (it has that gear icon). When trying to view the error from the localhost (i.e. the server itself), it doesn't find the application on its path, even though the root web site works just fine from localhost. It is clearly not a firewall issue because first of all, the firewall is turned off, and second because the root web site works fine from localhost. Heck, I even tried connecting through telnet and that worked fine and dandy too, so it is most certainly and very clearly not a firewall issue. Basically, I just need to view the error at all. I won't have to fix this problem if I can just see the error and fix it, because obviously there is something wrong in the code itself... I just don't know what, because IIS/.NET won't tell me.

Runtime Error

Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.

Details: To enable the details of this specific error message to be viewable on remote machines, please create a tag within a "web.config" configuration file located in the root directory of the current web application. This tag should then have its "mode" attribute set to "Off".

So what I've already tried is what the error message itself suggests by setting the customErrors thing to "Off". In fact, it always was on "Off" so I didn't have to change anything. I've made sure that the web.config XML is valid. Another common reason for this error is that the .NET run-time is set to version 1.1, not 2.0. I've also made sure that this is correctly configured to 2.0. I'm running it in an independent application pool, meaning that there are no other applications at all, much less 1.1 applications, on the same application pool. I've made sure that EVERYONE can do ANYTHING to the files and directories in the application itself. I understand the security ramifications here, I'm just trying to get it working at all, and then I'll constrain the access rights afterward, one step at a time. But in any case, everyone can read those files.