All keys working as the tab key
 

I recently bought a new PC with Windows Vista and installed among others also
Excel 2007. When I try to use my old Excel files from the Office 2000 package
some of them won't allow me to enter figures or text - irrespectful of which
key I apply then the selected field just shifts to the next field to the
right. I can't find any logic in it - the problem seems to be with files
where access is protected, but not with all of them. I have tried to change
formatting but without success.