Can't get excel to sort all the way down

alice_greenwood 

There is no reason that Excel 365 should not be capable of sorting 10 000 lines of data.

I assume that, since you mention Excel 2007, the sorting you have in mind is the interactive process initiated from the Data Ribbon tab?  With 365 you have another option of leaving your source data untouched and using a formula (SORT or SORTBY functions) to reorder your data by one or more columns, ascending or descending).

If the sorted data is the same, it might be that your data is not what it appears.  There might be spurious non-printing characters hidden within the strings.  The LEN function will confirm the count of characters.  It is also possible to return the Unicode for each character using

= UNICODE(MID(data, {1,2,3,4,5,6}, 1))