saving to excel-----read only?

when I tried to save data from vb application to excel sheet, sometimes it shows the excel file is readonly and ask me to make a copy of it. But actually when I checked the property of the excel file, it's not marked readonly at all,
how could I get rid of this?

did you open the excelsheet while your project was runing?
then you might get this error.
also check your task manager.
if several excel.exe are running u mite get this errror.