Assuming you have dates in column A from A2 down and the start times are
from B2, end times from C2

you could use this formula in D2 and copy down column

=IF(SUMPRODUCT(--(A$1:A$10+B$1:B$10<A1+B1),--(A$1:A$10+C$1:C$10A1+B1)),"oops!","")


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daddylonglegs
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