If you have excel 2003 file but this actually have excel 2007 original sometime you can't open it in normal way, usually there is some warning that your file can't work properly. If you force it to open in 2003 format you will get file incomplete format, such as there are no line anymore, etc.To avoid this happen you can right click on the file then save as, then you choose keep in format excel 2007 by enable macro. This format can chose on the Save As Type option like on the below picture.
After you choose the Save As Type as you want, you can give those file what as you want it, and then you can open it like the original file look like. This procedure similar with covert office from 2007 to 2003.
This abnormality usually when you use computer with many kind of office, sometime you use 2003 office and sometime you use 2007 office, and you copy of certain file from different kind of office. Some contain of that file look like corrupt but actually just not unable to open on certain office, usually if you have file from higher grade and open in the lower grade.