Bug with Date

Question

While working on a project I've ran across a pretty nasty bug
with the Date class in flash. I've tested this in 8.0 Professional
and the issue also exists in 9.0 Alpha Release.
var d1:Date = new Date(2006, 12, 21);
var d2:Date = new Date(2007, 1, 31);
trace(Math.floor((d2.getTime() - d1.getTime()))/ 86400000);
This bit of code will trace 42 days which is correct.
Now try this:
var d1:Date = new Date(2006, 12, 21);
var d2:Date = new Date(2007, 2, 1);
trace(Math.floor((d2.getTime() - d1.getTime()))/ 86400000);
It traces out 39.
So how can a day one day later be 3 days less? Nice eh?
I further tested
var d1:Date = new Date(2006, 12, 21);
var d2:Date = new Date(2007, 12, 21);
trace(Math.floor((d2.getTime() - d1.getTime()))/ 86400000);
Which traces 365 and is correct. It appears there is some
time frame in Febuary, I haven't defined the range that has
problems.

Answer 1

12 is not a valid 2nd parameter in the date object in flash.
try 11 if you want to designate december.