Output to Excel Formats Dates Incorrectly

I am running a proprietary Access application that outputs data to Excel for Analysis. I need to do some basic date computatations but I can't because I can't properly format the dates in Excel. I've tried several solutions without success. I've highlighted the column, right clicked it then tried to format it as a date, I've used the text to number, then tried to format as a date. That produced ########### characters which I understand is an undersized cell indication but I couldn't seem to make the cell large enough to show me the date. Is there a setting I can use that will make the date issue a little easier to manage? Thanks