You could have code in the workbook or an add-in which may be causing the
error.
You could try opening the file in "safe" mode
windows start button|Run
excel /safe
Look for Workbook_Open or Aut

pen code.
Go to Tools>Add-ins and uncheck any strange add-ins. Maybe uncheck all and
recheck until you find the offender.
Gord Dibben Excel MVP