I've been a long-time DNN user and finally moved off my W2k3 server and IIS6. I like the new (to me) DNN 7.4, but I'm having an issue editing pages. I'm running on Windows Server 2012 R2 Essentials

When I click 'Edit this Page' on the Controlbar, nothing happens (in fact, none of the menu items do anything when clicked, but the check boxes check and uncheck...)

I've tried the first two suggestions on the Wiki entry for this:

http://www.dnnsoftware.com/wiki/page/problems-with-edit-mode including setting  <modules runAllManagedModulesForAllRequests="true"> and checking that "Newtonsoft.Json.dll" is in the BIN folder.

The next thing to try is to move to the Ribbonbar, but when going to Host Settings, I get this:

Error: Host Settings is currently unavailable.DotNetNuke.Services.Exceptions.ModuleLoadException: An item with the same key has already been added. ---> System.ArgumentException: An item with the same key has already been added. at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector) at DotNetNuke.Modules.Admin.Host.HostSettings.BindData() at DotNetNuke.Modules.Admin.Host.HostSettings. (EventArgs e) --- End of inner exception stack trace ---

Any suggestions?