AJAX not working on 1.8

Admin pages are not showing controls.  As an example, if I try to edit a customer role, most of the page displays, but then errors with....

AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts. Ensure the correct version of the scripts are referenced. If you are using an ASP.NET ScriptManager, switch to the AjaxScriptManager in System.Web.Ajax.dll, or use the ToolkitScriptManager in AjaxControlToolkit.dll.

This is after an upgrade to 1.8 which seemed to go well.

Thanks for any help.

I do suggest you to recompile the whole installation; Probably you performed the upgrade on a production website and some files were locked by iis