Error Accessing CRM 2011 Online Plugin-Registration Tool

This can be a frustrating error when trying to access CRM 2011 Online via the plugin registration tool:

Unhandled Exception: System.ServiceModel.Security.MessageSecurityException: An unsecured or incorrectly secured fault was received from the other party. See the inner FaultException for the fault code and detail.

Server stack trace:
   at System.ServiceModel.Channels.SecurityChannelFactory`1.SecurityRequestChannel.ProcessReply(Message reply, SecurityProtocolCorrelationState correlationState, TimeSpan timeout)
   at System.ServiceModel.Channels.SecurityChannelFactory`1.SecurityRequestChannel.Request(Message message, TimeSpan timeout)
   at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
   at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
   at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
   at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)

Exception rethrown at [0]:
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at Microsoft.IdentityModel.Protocols.WSTrust.IWSTrustContract.Issue(Message message)
   at Microsoft.IdentityModel.Protocols.WSTrust.WSTrustChannel.Issue(RequestSecurityToken rst, RequestSecurityTokenResponse& rstr)
   at Microsoft.Xrm.Sdk.Client.ServiceConfiguration`1.AuthenticateLiveIdInternal(ClientCredentials clientCredentials, SecurityTokenResponse deviceToken, String keyType)
   at Microsoft.Xrm.Sdk.Client.ServiceConfiguration`1.AuthenticateDevice(ClientCredentials clientCredentials)
   at Microsoft.Xrm.Sdk.Client.DiscoveryServiceConfiguration.AuthenticateDevice(ClientCredentials clientCredentials)
   at PluginRegistrationTool.CrmConnection.get_DiscoveryService() in C:\Projects\CRM 2011 SDK\sdk\tools\pluginregistration\CrmConnection.cs:line 272
   at PluginRegistrationTool.CrmConnection.RetrieveOrganizations() in C:\Projects\CRM 2011 SDK\sdk\tools\pluginregistration\CrmConnection.cs:line 367
   at PluginRegistrationTool.ConnectionsForm.OpenConnection(CrmConnection con) in C:\Projects\CRM 2011 SDK\sdk\tools\pluginregistration\ConnectionsForm.cs:line 940
Inner Exception: System.ServiceModel.FaultException: Invalid Request

Luckily, there is a pretty simple fix. Open up your %userprofile%\LiveDeviceID\ folder, and delete LiveDevice.xml (back it up in case something goes wrong!).

Restart the plugin registration tool, and it should now connect properly!