Problem using AutomaticUpdater for .NET 4.0 on .NET 2.0

Hello-

I am having trouble getting aU 2.6 working. I have upgraded to .NET 4.0 and aU 2.6 (latest) but am getting the following error when I try to run my app. I am using the .NET 2.0 version as I can't seem to get the 4.0 .dll to installed as a reference in VS 2008. Hope this provides enough clues, thanks...

----System.BadImageFormatException was unhandled Message="Could not load file or assembly 'AutomaticUpdater, Version=2.6.1.0, Culture=neutral, PublicKeyToken=d2050be9b2e72e40' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded." Source="Anesthesia" FileName="AutomaticUpdater, Version=2.6.1.0, Culture=neutral, PublicKeyToken=d2050be9b2e72e40" FusionLog="=== Pre-bind state information ===\r\nLOG: User = wjsBox\\wjs\r\nLOG: DisplayName = AutomaticUpdater, Version=2.6.1.0, Culture=neutral, PublicKeyToken=d2050be9b2e72e40\n (Fully-specified)\r\nLOG: Appbase = file:///C:/Users/wjs/Desktop/ODVersions/opendental7.2b/opendental7.2/OpenDental/bin/Release/\r\nLOG: Initial PrivatePath = NULL\r\nCalling assembly : Anesthesia, Version=7.2.3857.17543, Culture=neutral, PublicKeyToken=null.\r\n===\r\nLOG: This bind starts in default load context.\r\nLOG: Using application configuration file: C:\\Users\\wjs\\Desktop\\ODVersions\\opendental7.2b\\opendental7.2\\OpenDental\\bin\\Release\\OpenDental.vshost.exe.Config\r\nLOG: Using machine configuration file from C:\\Windows\\Microsoft.NET\\Framework\\v2.0.50727\\config\\machine.config.\r\nLOG: Post-policy reference: AutomaticUpdater, Version=2.6.1.0, Culture=neutral, PublicKeyToken=d2050be9b2e72e40\r\nLOG: Attempting download of new URL file:///C:/Users/wjs/Desktop/ODVersions/opendental7.2b/opendental7.2/OpenDental/bin/Release/AutomaticUpdater.DLL.\r\nERR: Failed to complete setup of assembly (hr = 0x8013101b). Probing terminated.\r\n" StackTrace: at Anesthesia.FormAnestheticRecord.InitializeComponent() at Anesthesia.FormAnestheticRecord..ctor(Patient patCur, AnestheticData AnestheticDataCur) at Anesthesia.FormOpenDentalP.menuItemAnestheticRecord_Click(Object sender, EventArgs e) at System.Windows.Forms.MenuItem.OnClick(EventArgs e) at System.Windows.Forms.MenuItem.MenuItemData.Execute() at System.Windows.Forms.Command.Invoke() at System.Windows.Forms.Command.DispatchID(Int32 id) at System.Windows.Forms.Control.WmCommand(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.Form.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(Form mainForm) at OpenDental.ProgramEntry.Main(String[] args) in C:\Users\wjs\Desktop\ODVersions\opendental7.2b\opendental7.2\OpenDental\Main Modules\ProgramEntry.cs:line 44 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: