No that is correct: Things don't have a sector associated until DetermineSector() is called on it. This is done because it is not doable to figure out in which sector a thing is at a real-time speed for large maps (it would have to be called every time things are moved and when the map is loaded).

Still though, undo/redo should work.

It would be nice to see working steps-to-reproduce for this bug report!

http://support.microsoft.com/kb/810098 ? I am also very sure that this error CAN be caused by incorrect net framework version. And that DB doesn't even start without the proper framework that does not mean other programs don't too.

Please, don't say things you don't know for sure. Especially not here where we try to solve problems. The link you just pasted is completely unrelated. Doom Builder is not an ASP.NET webpage and doesn't use any database serivce (ADODB in this article).

The whole reason why I joined this forum is for the undo crash! It happens to me when I do it too fast. If DB2 saved undo/redo actions, I could reproduce it for you. Ya know, maybe have a "final" save to dump all of that info for a final release. Other than that, I'm no programmer and don't have the means to recreate it other than saying I do it too fast. I will post the details when it happens next.

EDIT: The above mention of "too fast" only happens in 2D mode that I can remember. Here is what just happened:
-(2D mode)
-added thing
-edited thing into cyberdemon
-dragged thing
-dragged linedef to fit cyberdemon thing
-visual mode
-(began undo sequence)
The crash may have occurred between the undo of editing thing into cyberdemon and adding thing but I can't be sure. It showed me the dragged linedef undo so it was either editing thing's undo or dragging thing's undo.
My version number is 2.0.1.1157 and attached is the log and cfg. Below are the details and sorry--don't know what the Hell code tags are!

------------------------------------------------------------------------------------------------------------

See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
at System.ThrowHelper.ThrowKeyNotFoundException()
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
at CodeImp.DoomBuilder.VisualModes.VisualMode.DoCulling()
at CodeImp.DoomBuilder.BuilderModes.BaseVisualMode.ResourcesReloadedPartial()
at CodeImp.DoomBuilder.VisualModes.VisualMode.OnUndoEnd()
at CodeImp.DoomBuilder.BuilderModes.BaseVisualMode.OnUndoEnd()
at CodeImp.DoomBuilder.Editing.UndoManager.PerformUndo(Int32 levels)
at CodeImp.DoomBuilder.Editing.UndoManager.PerformUndo()
at CodeImp.DoomBuilder.Actions.Action.Begin()
at CodeImp.DoomBuilder.Actions.ActionManager.BeginActionByKey(Int32 key, Boolean repeated)
at CodeImp.DoomBuilder.Actions.ActionManager.KeyPressed(Int32 key)
at CodeImp.DoomBuilder.Windows.MainForm.MainForm_KeyDown(Object sender, KeyEventArgs e)
at System.Windows.Forms.Control.OnKeyDown(KeyEventArgs e)
at System.Windows.Forms.Control.ProcessKeyEventArgs(Message& m)
at System.Windows.Forms.Form.ProcessKeyPreview(Message& m)
at System.Windows.Forms.Control.ProcessKeyMessage(Message& m)
at System.Windows.Forms.Control.WmKeyChar(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


************** Loaded Assemblies **************
mscorlib
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3603 (GDR.050727-3600)
CodeBase: file:///c:/WINDOWS/Microsoft.NET/Framework/v2.0.50727/mscorlib.dll
----------------------------------------
Builder
Assembly Version: 2.0.1.1157
Win32 Version: 2.0.1.1157
CodeBase: file:///C:/Program%20Files/Doom%20Builder%202/Builder.exe
----------------------------------------
System
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System/2.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Windows.Forms
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Windows.Forms/2.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System.Drawing
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Drawing/2.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
SlimDX
Assembly Version: 2.0.7.41
Win32 Version:
CodeBase: file:///C:/WINDOWS/assembly/GAC_32/SlimDX/2.0.7.41__b1b0c32fd1ffe4f9/SlimDX.dll
----------------------------------------
msvcm80
Assembly Version: 8.0.50727.4053
Win32 Version: 8.00.50727.4053
CodeBase: file:///C:/WINDOWS/WinSxS/x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_e6967989/msvcm80.dll
----------------------------------------
BuilderModes
Assembly Version: 2.0.1.1157
Win32 Version: 2.0.1.1157
CodeBase: file:///C:/Program%20Files/Doom%20Builder%202/Plugins/BuilderModes.dll
----------------------------------------
System.Design
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3053 (netfxsp.050727-3000)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Design/2.0.0.0__b03f5f7f11d50a3a/System.Design.dll
----------------------------------------
Sharpzip
Assembly Version: 0.85.2.329
Win32 Version: 0.85.2.329
CodeBase: file:///C:/Program%20Files/Doom%20Builder%202/Sharpzip.DLL
----------------------------------------
TrackBar
Assembly Version: 1.0.2486.37933
Win32 Version: 1.0.2486.37933
CodeBase: file:///C:/Program%20Files/Doom%20Builder%202/TrackBar.DLL
----------------------------------------

************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.

For example:

<configuration>
<system.windows.forms jitDebugging="true" />
</configuration>

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.

------------------------------------------------------------------------------------------------------------

Thanks.

That bug is actually pretty easy to reproduct:

1) Open/Start new map
2) Insert thing
3) Go to 3d mode and undo twice (first undo will only undo the thing editing)
4) Profit! Er... I mean crash

Actually if it crashes or not depends on where you are looking in 3d mode: only looking at the position where the thing used to be will make it boom.

Fixed.