Exception in customization

I modified a customization to move some fields around. When I finished and saved everything looked okay, but when I opened up the screen the next time I got this error:

Message: Exception has been thrown by the target of an invocation.
Inner Exception Message: ‘child’ is not a child control of this parent.
Program: CommonLanguageRuntimeLibrary
Method: InvokeMethod

After this I see the screen but some parts of it don’t look right, and the menu and toolbars are completely missing. I can bring up the customization tools dialog by right clicking on a blank space in the dialog, but how can I troubleshoot what went wrong and fix it? All I did was move components around and resize them.

For future reference, I fixed this under Customization Maintenance. Menu Actions -> Show Custom Data under the Controls tab I found a field with no ParentControlKey. I looked at the controls under the Properties tab and found the Key for what I guessed was the correct parent and set the ParentControlKey to this value.