Prompted for the VBA project password on Workbook close

Been using this invoice for years, now have this problem once in a while.Does not always request password on close, seems like it only happens when I'm online and the file does a syn with dropbox.Do not have google search on computer,only common add-in is adobe acobat, it has all updates. Anybody had this problem,and where do I start to debug?.When it promptes for password and I type it in it says invalid,not sure what going on.Running Office 2013.

Thanks Z