[v0.6.0.8] File->Reset crashes the application

## What is the expected output? What do you see instead?
Clicking on File->Reset leads to application crashes. This happens on three PCs 
two of them using the same hardware and a third one using a different hardware. 
It does not always happen but is easily reproducible.

It seems that there are two different behaviors, depending on whether logging 
in activated or not:
- if logging is on, "Reset" crashes the application with bug report 1
- if logging is off, "Reset" crashes the application with two crash reports 
(see reports 2 and 3), both different from the first report.

## What version of the product are you using? On what operating system?
- OHM v0.6.0.8alpha
- Device type 1:
|-- Win7 64-bit Professional SP1, one PC English, the other German
|-- Mainboard: MSI MS-9834
|-- CPU: Core 2 Duo P8600 2.4GHz
-Device type 2:
|-- Win7 64-bit Professional SP1, English
|-- Mainboard: Roda DR886EX
|-- CPU: Core 2 Duo U7500 1.06GHz

## Please attach a Report created with "File / Save Report...".
- report 1:
Version: 0.6.0.8

System.AccessViolationException: Attempted to read or write protected memory. 
This is often an indication that other memory is corrupt.
   at System.Management.SecuredConnectHandler.ConnectNSecureIWbemServices(String path, IWbemServices& pServices)
   at System.Management.ManagementScope.InitializeGuts(Object o)
   at System.Management.ThreadDispatch.ThreadEntryPointMethodWithParam()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

Common Language Runtime: 4.0.30319.1
Operating System: Microsoft Windows NT 6.1.7601 Service Pack 1
Process Type: 64-Bit

- report 2:
Version: 0.6.0.8

System.NullReferenceException: Object reference not set to an instance of an 
object.
   at OpenHardwareMonitor.Utilities.Logger.SensorRemoved(ISensor sensor)
   at OpenHardwareMonitor.Utilities.Logger.HardwareRemoved(IHardware hardware)
   at OpenHardwareMonitor.Hardware.HardwareEventHandler.Invoke(IHardware hardware)
   at OpenHardwareMonitor.Hardware.Computer.Remove(IGroup group)
   at OpenHardwareMonitor.Hardware.Computer.Close()
   at OpenHardwareMonitor.GUI.MainForm.resetClick(Object sender, EventArgs e)
   at System.Windows.Forms.Command.Invoke()
   at System.Windows.Forms.Control.WmCommand(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at OpenHardwareMonitor.GUI.MainForm.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Common Language Runtime: 4.0.30319.1
Operating System: Microsoft Windows NT 6.1.7601 Service Pack 1
Process Type: 64-Bit

- report 3:
Version: 0.6.0.8

System.NullReferenceException: Object reference not set to an instance of an 
object.
   at OpenHardwareMonitor.Utilities.Logger.SensorRemoved(ISensor sensor)
   at OpenHardwareMonitor.Utilities.Logger.HardwareRemoved(IHardware hardware)
   at OpenHardwareMonitor.Hardware.HardwareEventHandler.Invoke(IHardware hardware)
   at OpenHardwareMonitor.Hardware.Computer.Remove(IGroup group)
   at OpenHardwareMonitor.Hardware.Computer.Close()
   at OpenHardwareMonitor.GUI.MainForm.MainForm_FormClosed(Object sender, FormClosedEventArgs e)
   at System.Windows.Forms.FormClosedEventHandler.Invoke(Object sender, FormClosedEventArgs e)
   at System.Windows.Forms.Form.RaiseFormClosedOnAppExit()
   at System.Windows.Forms.Application.ExitInternal()
   at System.Windows.Forms.Application.Exit(CancelEventArgs e)
   at OpenHardwareMonitor.Program.Application_ThreadException(Object sender, ThreadExceptionEventArgs e)
   at System.Windows.Forms.Application.ThreadContext.OnThreadException(Exception t)
   at System.Windows.Forms.NativeWindow.Callback(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(IntPtr 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 OpenHardwareMonitor.Program.Main()

Common Language Runtime: 4.0.30319.1
Operating System: Microsoft Windows NT 6.1.7601 Service Pack 1
Process Type: 64-Bit
Original issue reported on code.google.com by aktaru...@caramail.com on 14 Aug 2013 at 1:29
Merged into: #7
wintomo / open-hardware-monitor

[v0.6.0.8] File->Reset crashes the application #497
