Visual Studio 2010 puts 4.0 classes into 3.5 ASP.NET project

[IreneT]

Hi,



I have existing ASP.NET 3.5 project I migrated to Visual Studio 2010. I
didn't migrate it to .NET 4.0. Every time I try to edit .aspx page, it
alters the .designer.cs class to point to
System.Web.UI.WebControls.WebParts.UpdatePanel class instead of
System.Web.UI.UpdatePanel class and then the build of course produces an
error. The project properties says ".NET3.5".



Also the "design" tab produces just one box saying "unknown server tag
asp:UpdatePanel". It seems like it is looking at .NET4.0 to generate the
design view, not 3.5.

Is there a setting somewhere I need to change?



Any help will be appreciated.



Thanks,


Irene