I've been breaking my head for a couple of days about an issue that is so obvious i missed it!
I decided to create a new virtual machine (using Virtual PC 2007) running Vista Ultimate, SQL Server 2008 and VS2008. Installing all software went just fine, and after a few cups of coffee i was able to install and run DNN from within the virtual machine. All was fine untill i opened up a module project containing an ASP.NET AJAX UpdatePanel.
That was about the same time i noticed that none of the AJAX controls (like UpdatePanel, ScriptManager) where available in the Toolbox. In design mode, my i saw an error "failed to create designer" wher.e my update panel was supposed to be.
Now, i like Google a lot, but i had no luck finding anything related to my issue. I tried to rebuild the Toolbox, but to no avail. A repair install of VS2008 had no effect either. As a last resort i decided to reinstall VS2008 completely. No effect. No i was getting a bit worried... my plan for a virtual develop environment was falling apart.. or was it?
Suddenly i tried the obvious: create a new website project in Visual Studio and PRESTO: all my AJAX control were there? To my horror I have to confess that just at that moment I remembered that AJAX is built in in ASP.NET 3.5, and available as an extension to ASP.NET 2.0. As all my modules are still ASP.NET 2.0, and i run my DNN sites in ASP.NET 2.0 as well, of course the AJAX extensions were not available.
As it turned out.. a simple installation of the ASP.NET 2.0 AJAX extensions fixed my problem. Well.. another lesson learned I guess: never expect Microsoft to think about everything..... Wouldn't you agree that it would have been much more logical if the Visual Studio setup also installed the ASP.NET 2.0 AJAX Extensions?