This may provide a clue, from debug.log:
Application Information
----------------------------------------------------------------------------
Version: 6.0.6.1733
Command Line: C:\Program Files\Eraser\Eraser.exe
Exception Information (Outermost to innermost)
----------------------------------------------------------------------------
Exception 1:
Message: Window handle already exists.
Exception Type: System.InvalidOperationException
Stack Trace [0]: at System.Windows.Forms.NativeWindow.CheckReleased()
Stack Trace [1]: at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp)
Stack Trace [2]: at System.Windows.Forms.Control.CreateHandle()
Stack Trace [3]: at System.Windows.Forms.Form.CreateHandle()
Stack Trace [4]: at Eraser.MainForm..ctor()
Stack Trace [5]: at Eraser.Program.OnGUIInitInstance(Object sender)
Stack Trace [6]: at Eraser.GUIProgram.Run()
Stack Trace [7]: at Eraser.Program.GUIMain(String[] commandLine)
Stack Trace [8]: at Eraser.Program.Main(String[] commandLine)
Application Information
----------------------------------------------------------------------------
Version: 6.0.6.1733
Command Line: C:\Program Files\Eraser\Eraser.exe
Exception Information (Outermost to innermost)
----------------------------------------------------------------------------
Exception 1:
Message: Window handle already exists.
Exception Type: System.InvalidOperationException
Stack Trace [0]: at System.Windows.Forms.NativeWindow.CheckReleased()
Stack Trace [1]: at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp)
Stack Trace [2]: at System.Windows.Forms.Control.CreateHandle()
Stack Trace [3]: at System.Windows.Forms.Form.CreateHandle()
Stack Trace [4]: at Eraser.MainForm..ctor()
Stack Trace [5]: at Eraser.Program.OnGUIInitInstance(Object sender)
Stack Trace [6]: at Eraser.GUIProgram.Run()
Stack Trace [7]: at Eraser.Program.GUIMain(String[] commandLine)
Stack Trace [8]: at Eraser.Program.Main(String[] commandLine)