Adding missing date rows to spreadsheet

I receive a spreadsheet each month from another source that has about 5-6000 rows. They are listings of call statistics, with approx 12 columns of data per each dated row. The problem is that if there were no call statistics for a given date, that row is not represented on the spreadsheet. For example if there was data on August 1-3 then 5-6 then 8-9, the (column A) date field would look like:

8/01/08 - Category one
8/02/08 - Category one
8/03/08 - Category one
8/05/08 - Category one
8/06/08 - Category one
8/08/08 - Category one
8/09/08 - Category one
...and so on down to 8/31/08 where Category 2 will start with it's 31 dates, then Category 3 and so on...

I'm looking for a way to check the dates and if one is missing (like the 4th or 7th) to insert a row "with" the missing date entered in the column A cell, and also fill in all the other columns of the newly inserted row with zeros.

The dates would always be for the same month and year on all 5-6000 rows, so only the "day" would need to be searched for and changed.

The reason I need every row dated is because I am using it as a join field for another table in MS Access, after I import the data from Excel to Access.

Thanks for your help /Mike