Fix Excel cannot complete this task with available resources, Not enough System Resources to Display Completely, There isn't enough memory to complete this action errors.

Whenever I try to open this .dat file in Excel, it loads about halfway and displays the error "File not loaded completely". Why does it do this and how can it be opened?

The theoretical limit of rows and columns in the Microsoft Office application Excel is well defined. If you exceed this mark, you are prompted with a ‘File not loaded completely’ popup message ...