So, over the holidays I migrated the ASP.NET 1.1 web app to ASP.NET 3.5. I had initially wanted to use the migration tools provided by Microsoft but I also wanted to remove some junk controls that were already part of the application and wanted to spend some time refactoring some logic so I decide to create a new application and port code over one page at a time and clean/re factor as I went. During this re-write I added some Ajax calls and also added UpdatePanels hoping to make the user experience better. Well while unit testing on my local box everything went well but once I push the code to the Dev server my GridView controls no longer worked as expected using IE 7 but worked fine in Chrome and FireFox.
I googled the heck out of Ajax/gridview and also visited some personal favorite blogs like Scott Guthrie where I found this blog http://weblogs.asp.net/scottgu/archive/2006/12/10/gotcha-don-t-use-xhtmlconformance-mode-legacy-with-asp-net-ajax.aspx. I found in the Dev web.config the <xhtmlConformance mode="Legacy" /> so I commented it out, even restarted IIS and no joy. The fix, at least for me was not removing <xhtmlConformance mode="Legacy" /> but switching it to <xhtmlConformance mode="Transitional" />