I am having a problem regarding clipboard and I get this error
message every time I try to make a copy / paste operation from
an Excel file.  The code breaks at Clipboard.GetDataObject() and
the message error is this:  OpenClipboard Failed (Exception from
HRESULT: 0x800401D0 (CLIPBRD_E_CANT_OPEN))  My WPF application
is already running when I open Excel, write some text and then
try to copy / paste.  The code that I'm using is this:  private
void SetClipboardData() { IDataObject data =
Clipboard.GetDataObject(); IList result =
GetDataForFileDropFormat( data ); if ( ( result != null ) && (
result.Count > 0 ) ) { this._elementsClipboard = result;
this._sourceDrag = null; this._sourceClipboard = null;  The
above function is called in this handler method:  public void
Handle_WM_DRAWCLIPBOARD( IntPtr hwnd, int msg, IntPtr wParam,
IntPtr lParam, ref bool handled ) {  SendMessage(
this._nextClipboardViewer, msg, wParam, lParam );  // get data
from clipboard  handled = true;  I have been searching MSDN and
.NET forum