I maen you can not see it. This is only happening with one file. I do not
get any error message. It opens excel (or if I do from excel it "appears to
be opening" ) - it has a password and YES I am sure I know it and excel
accepts it. Excel ask if I want read-only and it does not matter whether I
say yes or no.

In excel the file is listed under the File menu, but not under the Window
menu. When I close excel it asks if I want to save changes for this file,
which I have done nothing to!