Ask Paula!

You've probably just converted your vs 2005 web project with ajax to vs 2008. This is because Visual Studio 2008 has a newer, built-in version. The fix is short and sweet!  

Remove the System.Web.Extensions from references, then add them back again! That should connect you with the correct assembly. If you're uncertain how to remove the reference, check this out: http://geekswithblogs.net/AskPaula/archive/2008/09/04/124948.aspx   

Let's say you've converted a vs 2005 asp .net project over to vs 2008 and you have old ajax references like System.Web.Extensions, etc. that you want to get rid of, but they don't show up under the Solution view. The way to remove those references (or add new ones) is to do the following:

1. Right click on the solution (assuming the solution view is active)
2. Select Property pages
3. At the bottom of the dialog box you'll be able to Add, Remove or update.

The quickest way is to do the following:

1. Go to Start>Settings>Control Panel
2. Select Add/Remove Programs
3. Scroll unitl you find BizTalk
4. Click on the support anchor (see screen shot below)