title: problem with System.Web.Extension after installing .net 3.5 sp1
body: <p>I have a solution that includes several class library's and a website. The solution was built in .net 2.0 Visual Studio 2005, and later converted to .net 3.5 (all class library's and website are targeting 3.5 framework).
  Before installing the update, the website functioned perfectly. After, a build fails on 
  <code>using System.Web.Extensions;</code>
  the error message is: "<code>The type of namespace Extensions does not exist in the namespace System.Web (are you missing an assembly reference?)</code>".</p>
  
  <p>I looked in the .net 2.0 framework folder and the System.Web.Extensions .dll was indeed gone. However the C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5 folder had the .dll. the GAC shows two System.Web.Extensions, the old 1.06 version and the new 3.5 version. I have the web.config rebinding to the new version.</p>
  
  <p>I checked my references, deleted the old one and added a reference to  the .3.5 version of System.Web.Extensions. It didn't work, the build failed at the same place.</p>
  
  <p>I then copied the .dll to the bin of my website, and pointed the reference there. that also did not work, the solution did not build, and when I looked at the references, it appeared to not have a reference to the file in the bin folder.</p>
  
  <p>Note: The system has .net 1.1 installed, Visual studio 2003, and 2005.</p>
  
  <p>can anyone point me to what I can do to fix this?
  I know uninstalling the 3.5 sp1 update will fix it, but I'd rather keep it.</p>
  
  <p>Thank you
  Deb</p>