Hide Wrong Date

The problem I am having is that my sheet is formated so that I enter the first day of the month in A2 (01-02-2011) and in A3 the formula is A2+1 and so forth down. If I have not entered a date in A2 then A3 displays 01-01-1900 and so forth down.
Is there any way to make the cells stay empty until a date is entered in A2?

Thanks in Advance

Alan