I have a suggestion if you allow it:
in the list of conflicts why not specify the names of hours with the days
ex: ... activity (A1) is in conflict with activity (A2) in Tuesday (2) and Tuesday (4) ...
the numbers (2) and (4) are the names given by the user at the hours.
one of the advantages of this suggestion is to know if the activities are consecutive or not.
hmm... only if you know the duration. so that might be needed also.
OK, I wrote this down.