ASP.NET web application working incorrectly in IIS 7 (Windows Server 2008)

I have an ASP.NET we开发者_如何学编程b application that is not working correctly once deployed to IIS 7 on a Windows server 2008 box. The particular page is using an update panel and hides/shows drop down lists based off of a selection in a drop down list. The page is working perfectly locally using Cassini (the local webserver used by Visual Studio 2008), but loses the items from the drop downs and does not show and hide the controls upon callbacks from within the update panel.

I've googled around and have a suspicion it may have something to do with the Integrated vs. Classic pipeline in IIS 7. It's currently using the DefaultAppPool(Integrated). Can someone help me figure out what I should do???

It might be a problem with the version of the .NET framework installed on the server. It sounds like you're using the ASP.NET AJAX libraries that ship with .NET 3.5. Windows Server 2008 does not ship with .NET 3.5 by default (ref). It has to be installed separately.

Have you tried changing your sites Application Pool - Managed Pipline Mode to "Classic" instead of "Integrated"? I know in the past I've run into the same sort of problem in IIS7 when running in "Integrated" mode and using the following Url rewriter for my sites: UrlRewritingNet.UrlRewriter.dll

It turned out to be that the web application was running under another website whose web.config had set EnableViewstate to 'false' which was causing this child web application to incorrectly function.