Does anybody knows why I'm asked if I want to create a copy of excel files when openning them directly from Outlook Express ?
No, I guess nobody knows
Well I'll take a WAG. Maybe you've opened them before and somehow it wants to make a copy to not overwrite your original... Maybe your temp folder is somehow been changed to a protected directory, so outlook can't open it there?... Maybe your temp directory is full... Maybe your temp directory is not giving permissions to outlook... Maybe you already have the file open in Excel and it can't overwrite it because the file is locked being that it's already open.
Maybe if you can give a more specific details about what is going on you can get an answer that helps. does this only happen with excel files? files sent to yourself? hmmm the possibilities seem endless.