> Hello!
>
> I am writing a desktop application that uses multiple GUI threads to
> interact with the user.
> Secondary GUI thread creates a main form for this thread, having
> application's main form as its parent and calls
> System.Windows.Forms.Application.Run() with this newly created form.
> The problem is that, under certain conditions (described below) secondary
> GUI thread strangely crashes after it has exited the 'threadstart' function.
> The crash is 'Unhandled access violation exception' (0xc000000a) in
> ntdll.dll with the following call stack:
>
> ntdll.dll!_RtlFreeThreadActivationContextStack@0()  + 0x1eda4
> kernel32.dll!_ExitThread@4()  + 0x39
> kernel32.dll!_BaseThreadStart@8()  + 0x3d
>
>
> My environment is .NET 1.1, Microsoft Windows XP SP2.
>
> Condition for crash is that thread crashes only after I create and display a
> modal dialog box (another custom form), heaving main form for GUI thread #2
> as Parent. This dialog box is used to display messages to the user instead
> of System.Windows.Forms.MessageBox (it has enhanced functionality like
> "Don't show this anymore" checkbox and timeout timer allowing it to be
> dismissed if user haven't clicked any buttons. When I switch back to
> System.Windows.Forms.MessageBox everything is fine.
>
> As this issue occurs in a big solution, I created new simple little
> CrashTest Project to isolate and simulate this behavior, but so far I
> haven't succeeded.
>
> Does anyone know what could cause this behaviour?
>
> Best regards,
> Alexei N. Adadurov
>
> (alexei.adadurov at super-lab dot ru)