Can't Load Plugin

Any idea how my plugin quit working? I tried removing it from the registry. This is what the command window shows if I drag drop it back into v7:

System.ArgumentException: The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
   at System.RuntimeType.GetGUID(Guid& result)
   at System.RuntimeType.get_GUID()
   at Rhino.PlugIns.PlugIn.Create(Type pluginType, String pluginName, String pluginVersion, Boolean useRhinoDotNet, Assembly pluginAssembly)
   at Rhino.Runtime.HostUtils.CreatePlugIn(Type pluginType, Assembly pluginAssembly, Boolean printDebugMessages, Boolean useRhinoDotNet)
   at Rhino.PlugIns.PlugIn.CreateFromAssembly(Assembly pluginAssembly, Boolean displayDebugInfo, Boolean useRhinoDotNet)
Unable to load Leo.Plugin.rhp plug-in: initialization failed.
Drag and drop unable to load plug-in C:\Users\EricM\source\repos\_RhinoCopy\Leo.Plugin.rhp

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