There is a pattern to these errors.  Same asp.net source, same database, same IIS version, same Visual Studio version, same components version, but still some chunk of JavaScript is absent without leave. The actual error messages tend to be new each time, but at least the pattern is recognizable. The reason is that the missing JavaScript functions live in webresource.axd, webresource.axd is handled by an aspnet_isapi.dll, and chances are you are missing a mapping for "axd" in your IIS configuration for your web site. To fix:

• In the IIS Microsoft Management Console snap-in, right-click the virtual directory and select Properties.
• On the Virtual Directory tab click the Configuration button. 
• On the Mappings tab of the Application Configuration dialog click the Add button. This brings you to the Add/Edit Application Extension Mapping dialog. Enter for the Executable the full path to aspnet_isapi.dll located in .NET framework directory.  In this case the path was C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll. Set the Extension to be ".axd".  Don't forget the dot or the dialog will not let you proceed. Uncheck the "Check that file exists" checkbox.
• If the OK button doesn't become enabled, there's a weirdity here (in the tech support business we used to call these "issues", in the real world we call it a "bug").  Click the Executable textbox entry and the OK button should become enabled.

Cycle the website and try again.  Different flavors of this problem occur periodically, so tag this page for later and save yourself some pain.