When trying to export data from grid to Excel Instance, I get an error:
"OLE error 800A03EC multiple Excel files open, retry with zero or one open Excel file."
This only occurs when saving as Excel Instance. It is not a problem when saving as Excel file or any other kind of format.
Issue with the "Start at Active Cell" option in the Save As window and the active cell being in Row 1 in the Excel Instance.
WORKAROUND 1:
Disable the "Start at Active Cell" option.
WORKAROUND 2:
Open Excel and select any cell that is not on Row 1 of the spread sheet.
Enable "Start at Active Cell" option in Toad's Save As.
Note: this will export data into Excel, start at whatever cell you've selected in Excel (that is off Row 1).
STATUS:
Waiting for fix in a future version of Toad for Oracle.