You can try deleting the temporary MSForms.exd files just once in these hidden temp folders:
C:\Users\[user.name]\AppData\Local\Temp\Excel8.0\MSForms.exd
C:\Users\[user.name]\AppData\Local\Temp\VBE\MSForms.exd
If you need to distribute your Excel file, there is a way to rename the MSForms.exd...