I tested my application with FastMM and FullDebugMode turned on, since I had some shutdown problems.

After solving bunch of my own problems FastMM started to complain about calling virtual method on a freed object in TPopupList. I tried to move the menus unit as early as possible in uses so that it would be finalized last, but it didn't help. Is this real problem, a bug in vcl or false alarm from FastMM?

Here's the full report from FastMM:

```
FastMM has detected an attempt to call a virtual method on a freed object. An access violation will now be raised in order to abort the current operation.

Freed object class: TPopupList

Virtual method: Offset +16

Virtual method address: 4714E4

The allocation number was: 220

The object was allocated by thread 0x1CC0, and the stack trace (return addresses) at the time was:
403216 [sys\system.pas][System][System.@GetMem][2654]
404A4F [sys\system.pas][System][System.TObject.NewInstance][8807]
404E16 [sys\system.pas][System][System.@ClassCreate][9472]
404A84 [sys\system.pas][System][System.TObject.Create][8822]
7F2602 [Menus.pas][Menus][Menus.Menus][4223]
40570F [sys\system.pas][System][System.InitUnits][11397]
405777 [sys\system.pas][System][System.@StartExe][11462]
40844F [SysInit.pas][SysInit][SysInit.@InitExe][663]
7F6368 [PCCSServer.dpr][PCCSServer][PCCSServer.PCCSServer][148]
7C90DCBA [ZwSetInformationThread]
7C817077 [Unknown function at RegisterWaitForInputIdle]

The object was subsequently freed by thread 0x1CC0, and the stack trace (return addresses) at the time was:
403232 [sys\system.pas][System][System.@FreeMem][2699]
404A6D [sys\system.pas][System][System.TObject.FreeInstance][8813]
404E61 [sys\system.pas][System][System.@ClassDestroy][9513]
428D15 [common\Classes.pas][Classes][Classes.TList.Destroy][2914]
404AB3 [sys\system.pas][System][System.TObject.Free][8832]
472091 [Menus.pas][Menus][Menus.Finalization][4228]
4056A7 [sys\system.pas][System][System.FinalizeUnits][11256]
4056BF [sys\system.pas][System][System.FinalizeUnits][11261]
7C9032A8 [RtlConvertUlongToLargeInteger]
7C90327A [RtlConvertUlongToLargeInteger]
7C92AA0F [Unknown function at towlower]

The current thread ID is 0x1CC0, and the stack trace (return addresses) leading to this error is:
4714B8 [Menus.pas][Menus][Menus.TPopupList.MainWndProc][3779]
435BB2 [common\Classes.pas][Classes][Classes.StdWndProc][11583]
7E418734 [Unknown function at GetDC]
7E418816 [Unknown function at GetDC]
7E428EA0 [Unknown function at DefWindowProcW]
7E428EEC [Unknown function at DefWindowProcW]
7C90E473 [KiUserCallbackDispatcher]
7E42B1A8 [DestroyWindow]
47CE31 [Controls.pas][Controls][Controls.TWinControl.DestroyWindowHandle][6857]
493BE4 [Forms.pas][Forms][Forms.TCustomForm.DestroyWindowHandle][4564]
4906D9 [Forms.pas][Forms][Forms.TCustomForm.Destroy][2929]

Current memory dump of 256 bytes starting at pointer address 7FF9CFF0:
2C FE 82 00 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 C4 A3 2D 0C 00 00 00 00 B1 D0 F9 7F
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 16 32 40 00 9D 5B 40 00 C8 5B 40 00
CE 82 40 00 3C 40 91 7C B0 B1 94 7C 0A 77 92 7C 84 77 92 7C 7C F0 96 7C 94 B3 94 7C 84 77 92 7C
C0 1C 00 00 32 32 40 00 12 5B 40 00 EF 69 40 00 BA 20 47 00 A7 56 40 00 BF 56 40 00 A8 32 90 7C
7A 32 90 7C 0F AA 92 7C 0A 77 92 7C 84 77 92 7C C0 1C 00 00 0E 00 00 00 00 00 00 00 C7 35 65 59
2C FE 82 00 80 80 80 80 80 80 80 80 80 80 38 CA 9A A6 80 80 80 80 80 80 00 00 00 00 51 D1 F9 7F
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 C1 00 00 00 16 32 40 00 9D 5B 40 00 C8 5B 40 00
CE 82 40 00 3C 40 91 7C B0 B1 94 7C 0A 77 92 7C 84 77 92 7C 7C F0 96 7C 94 B3 94 7C 84 77 92 7C
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```

I'm using Delphi 2007 and FastMM 4.97.

**Edit1:** I think the main problem here is why does Classes.StdWndProc call Menus.TPopupList? Digging the call stack inside debugger shows that System.FinalizeUnit is called three times, then it goes to SysUtils.ShowException, which tries to display MessageBox and after bunch of user32.dll calls we end up to classes.StdWndProc.

**Edit2:** I had problem with interfaces, fixing that made this problem go away. The object with interface was freed, but the reference was released later on. When the interface was released, occured an exception which I initially somehow ignored. Releasing the interface probably corrupted something which caused all other problems.