ADE 4.5 will not start

Suddenly ADE stopped opening. Uninstall/reinstall doesn't work. Deleting "/My Digital Edition/" doesn't work. If install 4.0 it works, and immediately asks to upgrade to 4.5, and as soon as I do that, it fails again. Every time I start ADE 4.5 I get the same exception in the Event Viewer:

Faulting application name: DigitalEditions.exe, version: 4.5.11.0, time stamp: 0x5e85fa7a
Faulting module name: KERNELBASE.dll, version: 10.0.19041.488, time stamp: 0x42f14898
Exception code: 0xe0434352
Fault offset: 0x00129962
Faulting process id: 0x414c
Faulting application start time: 0x01d690a4acd86ef5
Faulting application path: C:\Program Files (x86)\Adobe\Adobe Digital Editions 4.5\DigitalEditions.exe
Faulting module path: C:\WINDOWS\System32\KERNELBASE.dll
Report Id: 842795d7-9dfa-4ef2-8aee-e2f1b1de154c
Faulting package full name:
Faulting package-relative application ID:

And this is the stack trace:

Application: DigitalEditions.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Xml.XmlException
at System.Xml.XmlTextReaderImpl.Throw(System.Exception)
at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
at System.Xml.XmlTextReaderImpl.Read()
at System.Xml.XmlTextReader.Read()
at System.Configuration.XmlUtil..ctor(System.IO.Stream, System.String, Boolean, System.Configuration.ConfigurationSchemaErrors)
at System.Configuration.BaseConfigurationRecord.InitConfigFromFile()

Exception Info: System.Configuration.ConfigurationErrorsException
at System.Configuration.ConfigurationSchemaErrors.ThrowIfErrors(Boolean)
at System.Configuration.BaseConfigurationRecord.ThrowIfParseErrors(System.Configuration.ConfigurationSchemaErrors)
at System.Configuration.BaseConfigurationRecord.ThrowIfInitErrors()
at System.Configuration.ClientConfigurationSystem.OnConfigRemoved(System.Object, System.Configuration.Internal.InternalConfigEventArgs)

Exception Info: System.Configuration.ConfigurationErrorsException
at System.Configuration.ClientConfigurationSystem.OnConfigRemoved(System.Object, System.Configuration.Internal.InternalConfigEventArgs)
at System.Configuration.Internal.InternalConfigRoot.OnConfigRemoved(System.Configuration.Internal.InternalConfigEventArgs)
at System.Configuration.Internal.InternalConfigRoot.RemoveConfigImpl(System.String, System.Configuration.BaseConfigurationRecord)
at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(System.String, Boolean, Boolean, Boolean, Boolean, System.Object ByRef, System.Object ByRef)
at System.Configuration.BaseConfigurationRecord.GetSection(System.String)
at System.Configuration.ClientConfigurationSystem.System.Configuration.Internal.IInternalConfigSystem.GetSection(System.String)
at System.Configuration.ConfigurationManager.GetSection(System.String)
at System.Configuration.ClientSettingsStore.ReadSettings(System.String, Boolean)
at System.Configuration.LocalFileSettingsProvider.GetPropertyValues(System.Configuration.SettingsContext, System.Configuration.SettingsPropertyCollection)
at System.Configuration.SettingsBase.GetPropertiesFromProvider(System.Configuration.SettingsProvider)
at System.Configuration.SettingsBase.GetPropertyValueByName(System.String)
at System.Configuration.SettingsBase.get_Item(System.String)
at System.Configuration.ApplicationSettingsBase.GetPropertyValue(System.String)
at System.Configuration.ApplicationSettingsBase.get_Item(System.String)
at DE.ConfigurableWindowSettings.GetValue[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]](System.String)
at DE.ConfigurableWindowSettings.get_LibraryContentView()
at DE.MainWindow..ctor()
at DE.App.OnStartup(System.Windows.StartupEventArgs)
at System.Windows.Application.<.ctor>b__1_0(System.Object)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
at System.Windows.Threading.DispatcherOperation.InvokeImpl()
at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(System.Object)
at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
at MS.Internal.CulturePreservingExecutionContext.Run(MS.Internal.CulturePreservingExecutionContext, System.Threading.ContextCallback, System.Object)
at System.Windows.Threading.DispatcherOperation.Invoke()
at System.Windows.Threading.Dispatcher.ProcessQueue()
at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
at MS.Win32.HwndWrapper.WndProc(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
at MS.Win32.HwndSubclass.DispatcherCallbackOperation(System.Object)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority, System.TimeSpan, System.Delegate, System.Object, Int32)
at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr, Int32, IntPtr, IntPtr)
at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
at System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame)
at System.Windows.Threading.Dispatcher.PushFrame(System.Windows.Threading.DispatcherFrame)
at System.Windows.Application.RunDispatcher(System.Object)
at System.Windows.Application.RunInternal(System.Windows.Window)
at System.Windows.Application.Run(System.Windows.Window)
at System.Windows.Application.Run()
at DE.App.Main()