error: project not set up for debugging and none of the standard remedies work

[bvh]

When I try to run an asp.net project I get a message stating:

Error while trying to run project: Unable to start debugging on the
web server. The project is not configured to be debugged.

Selecting help as well as searching the web for this topic yeilds a
definitive answer. I'm supposed to set debug=true in my web.config
file.

My web config file has never said anything BUT debug=true. In fact
its just the normal file that VS creates:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

<system.web>

<!-- DYNAMIC DEBUG COMPILATION
Set compilation debug="true" to enable ASPX debugging.
Otherwise, setting this value to
false will improve runtime performance of this application.
Set compilation debug="true" to insert debugging symbols
(.pdb information)
into the compiled page. Because this creates a larger file
that executes
more slowly, you should set this value to true only when
debugging and to
false at all other times. For more information, refer to the
documentation about
debugging ASP.NET files.
-->
<compilation debug="true"/> etc...

I've seen other sites that mention adding localhost or machine name to
trusted sites. I tried that to no avail.

Other projects work just fine. I even created a new project and
brought in the files from the one that's broken and that version seems
to work. I tried copying the web config file over to the non-working
directory and that didn't do it either.

Is there anything else I can try? This is a very high profile site
and I really don't have time to test the DLL created by the second
project to make sure the namespaces aren't screwed up.