I do some spreadsheet creation here at work for various departments, so I use a brute force method of finding all instances of EXCEL and killing them, I warn the user about this when the program starts. My programs all have a GUI so they can say no, then shut there excel stuff down before running my program. Here is the code:

import wmi

def CloseXL(self):
try:
if self.xl is not None:
self.xlBook.Close(SaveChanges=0)
self.xl.Quit()
del self.xl
except AttributeError, err:
if err[0] != ‘xl’:
raise AttributeError, err

c = wmi.WMI()
if not self.NoExcel:
for process in c.Win32_Process(name=”excel.exe”):
process.Terminate()