app hungs when minimized for 30+ mins

hi all,
i have this problem: if i leave my app minimized for more than 30 mins, i can't bring it back again. it is hanged.
i attached the debugger and i've got the stack trace and error bellow.
if you have any idea/comment/suggestion about what goes wrong please help me

thanks in advance.
A.


first the error:
InvalidAsyncronousStateException in System.Windows.Forms.dll: An error occurred invoking the method. the destination thread no longer exists.

stack trace:

> System.Windows.Forms.dll!System.Windows.Forms.WindowsFormsSynchronizationContext.Send(System.Threading.SendOrPostCallback d, object state) + 0x9a bytes
  System.dll!Microsoft.Win32.SystemEvents.SystemEventInvokeInfo.Invoke(bool checkFinalization = true, object[] args = {Dimensions:[2]}) + 0x68 bytes
  System.dll!Microsoft.Win32.SystemEvents.RaiseEvent(bool checkFinalization = true, object key = {object}, object[] args = {Dimensions:[2]}) + 0x106 bytes
  System.dll!Microsoft.Win32.SystemEvents.OnUserPreferenceChanging(int msg, System.IntPtr wParam, System.IntPtr lParam) + 0x6f bytes
  System.dll!Microsoft.Win32.SystemEvents.WindowProc(System.IntPtr hWnd = 2688192, int msg = 8218, System.IntPtr wParam = 47, System.IntPtr lParam = 591990136) + 0x288 bytes
  [Native to Managed Transition]
  user32.dll!_InternalCallWinProc@20()  + 0x28 bytes
  user32.dll!_UserCallWinProcCheckWow@32()  + 0xa2 bytes
  user32.dll!_DispatchMessageWorker@8()  + 0xc8 bytes
  user32.dll!_DispatchMessageW@4()  + 0xf bytes
  [Managed to Native Transition]
  System.Windows.Forms.dll!System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(int dwComponentID, int reason = -1, int pvLoopData = 0) + 0x2ea bytes
  System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(int reason = -1, System.Windows.Forms.ApplicationContext context = {System.Windows.Forms.ApplicationContext}) + 0x17d bytes
  System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessageLoop(int reason, System.Windows.Forms.ApplicationContext context) + 0x53 bytes
  System.Windows.Forms.dll!System.Windows.Forms.Application.Run() + 0x2b bytes
  guiFrameworkManager.dll!guiFrameworkManager.FWManager.Run() Line 140 C#
  ixLoad.exe!IxLoad.IxLoad.Main(string[] i_args = {Dimensions:[0]}) Line 123 + 0xe bytes C#
  mscoree.dll!__CorExeMain@0()  + 0x34 bytes
  kernel32.dll!_BaseProcessStart@4()  + 0x23 bytes Start Free Trial