Validating and amending numbers entered via formula
 

I have a list of numbers in columns D & E that are calculated using a formula
eg.(=SUM((B2-B1)/0.02)*57.3066). The numbers in columns B & C are generated
automatically, and there is necessarily a roll-over at some point - ie they
count up to 6.28, then start again at 0. This means there is a number created
in the D & E columns that is orders of magnitude greater than the other
numbers in those columns, so I want a macro to find those numbers, and
replace them with the average of the number in the cell above, and the cell
below.
Can anybody tell me how to do this in Excel 2000?