Use the below function (changing [E:E]
to the appropriate range for your needs) to circumvent this issue (or change to any other format such as "mm/dd/yyyy"):
[E:E].Select
With Selection
.NumberFormat = "General"
.Value = .Value
End With
P.S. In my experience, this VBA solution works SIGNIFICANTLY faster on large data sets and is less likely to crash Excel than using the 'warning box' method.