When I open my Excel file and type in the password (my file is protected) than I get a message 
Please Login or Register  to view this content.
So I press YES and the file opens (aparently without any info lost and get the message 
Please Login or Register  to view this content.
More details I get: 
Please Login or Register  to view this content.
.
I can click on more details and get: 
Please Login or Register  to view this content.
When I close the file and safe the changing and wants to open again I get exactly the same error.

Does somebody have an idea what this error means and how it can be repaired?