Strange Error in ASP.NET C# Application

This one has me stumped. I'm looking at support files for a C# textbook,
including three ASP.NET applications that use Access databases. I create
virtual directories for the applications in IIS (running Win XP SP1 and Win
2000 SP4 dual boot - error occurs under either OS), then load the app into
the VS.NET 2003 IDE. When I attempt to run the application, I get the
following error in my browser, instead of the startup page:

Server Error in '/RoadSignReview' Application.

Compilation Error
Description: An error occurred during the compilation of a resource required
to service this request. Please review the following specific error details
and modify your source code appropriately.

Compiler Error Message: CS1595: 'RoadSignReview.RoadSigns' is defined in
multiple places; using definition from
'c:\WINNT\Microsoft.NET\Framework\v1.1.4322\Tempor ary ASP.NET
Files\roadsignreview\cebae5e1\8b8437d2\assembly\dl 2\da6e1f98\00031afb_ea55c3
01\RoadSignReviewCS.DLL'

Source Error:

Line 27:
Line 28:
[System.Runtime.CompilerServices.CompilerGlobalScop eAttribute()]
Line 29: public class RoadSigns_aspx : RoadSignReview.RoadSigns,
System.Web.SessionState.IRequiresSessionState {
Line 30:
Line 31:

Source File: c:\WINNT\Microsoft.NET\Framework\v1.1.4322\Tempora ry ASP.NET
Files\roadsignreview\cebae5e1\8b8437d2\ss6l2cvv.0. cs Line: 29

The above does not, of course, refer to anything the developer created.
And, just to make it even more fun, if I create this application myself on
the same PC (using the source code in the book), it runs OK.
Remember, this same phenomenon in *three different* apps.

If anybody has seen this and/or has any idea how to deal with it, I'd very
much appreciate some feedback.

--
************************************************** ********************
** All opinions are mine alone.Do not attribute elsewhere!
************************************************** ********************
** Peter van der Goes, Professor, Computers & Information Technology
** Rose State College
*********************** Contact ************************************
** Office e-mail: pvan@dotnet.itags.org.rose.edu
** Home e-mail: p_vandergoes@dotnet.itags.org.cox.net
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************************************************** ********************"codewriter" <code_writer_2003@.yahoo.com> wrote in message
news:hcfXa.319$pq5.100276@.news20.bellglobal.com...
> This question has been asked hundreds of times before, as far as I
remember.
> The couse is either conflicting assemblies for the same source or code
> behind tags are screwed up.
> Delete your dlls and recompile.
I appreciate the information. Works like a charm.
Somehow, I was unable to find this simple fix on my own, but I won't forget
it.
Thanks very much!