I have to thank you anyway because you are trying to solve a question
that will help me a lot in the everyday life using your free time.

Before to post the question I tried several solutions, but my knowledge
with Excel and mainly Vba are very very limited.

The routine is working well.
However if I modify the arrival date, lets say in B32 and then insert
another date in B33, the value in B32 is back to original value.
If I not asking to much is there a way to avoid to update the B32 if I
am not working on A32 cell?

Considering 3 as value in A20,
18-gen-2013 - 10:00 23-gen-2013 - 10:00 -- OK
19-gen-2013 - 0:00 24-gen-2013 - 0:00 -- OK
20-gen-2013 - 0:00 22-gen-2013 - 0:00 -- ??

In this case I'll use a conditional formatting to highlight the Sundays.

Thanks for your time and patiente. Congratulations for your high level
of knowledge of Excel/Vba
For how long did you learn to achieve this level?
Regards
Paul