Bizare error in published site

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I am working on a portal web application that is largely modular. I have
been working on it on a "developmen t" website. Some sections have been
tested and are complete. I decided to set up a Live website on the same
server so i could work on the development web site without affecting people
using the completed sections. I set up the website and then used VS 2005 to
"publish" the site. This seemed to work OK, it precompiled the whole site
and then published it to the new website. However when i access one
particular page on the live site i get the following very consuing error that
seems to be complaining about problems compiling temporary asp.net files that
seemingly have been created by the .net framework/compiler itself.

This error only occurs on one aspx page, the rest work fine and said page
works fine on the development website. The live website was utterly blank
when i "published" to it and i havn't done anything else to it since.

The werror is below and i am very puzzled, could anyone shed any light on
this, am i doing something wrong?

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: CS0433: The type 'VanSalesRoutes ' exists in both
'c:\WINDOWS\Mic rosoft.NET\Fram ework\v2.0.5072 7\Temporary ASP.NET
Files\portal\ed 2536d9\fef1a00a \assembly\dl3\8 0535391\3410a28 3_58b1c601\App_ Code.DLL'
and 'c:\WINDOWS\Mic rosoft.NET\Fram ework\v2.0.5072 7\Temporary ASP.NET
Files\portal\ed 2536d9\fef1a00a \assembly\dl3\b 5ff8697\3cbfd18 3_58b1c601\App_ Web_g_ksc0ps.DL L'

Source Error:

Line 110:
Line 111: [System.Runtime. CompilerService s.CompilerGloba lScopeAttribute ()]
Line 112: public class vansalesroutes_ aspx : global::VanSale sRoutes,
System.Web.Sess ionState.IRequi resSessionState , System.Web.IHtt pHandler {
Line 113:
Line 114: private static bool @__initialized;