Date class has a bug related to the daylight savings.
If you want to change the date using number of seconds it will cause a problem going over the dates when daylight savings change.
E.g.
private var mydate:Date = new Date(2008, 3, 4, 0, 0, 0, 0);
mydate = new Date (mydate.getTime() + 1000 * 60 * 60 * 24)
mydate = new Date(mydate);
If it goes over the date when daylight savings is changed, instead of adding 24 hours it will add 23 or 25 hours (depending on the time of the year – summer or winter)
So, to do perform Date manipulation correctly you have to use date field, i.e.:
mydate.date +=1;
This method correctly handles the daylight savings and it will keep initial 00:00:00 time.