However I recently noticed that it sometimes shows an incorrect age, and I can't figure out why. Sometimes it shows the person's age as being one year older than they really are, and sometimes one year younger than they really are. I've double-checked the formula used (and even deleted the custom field and re-added it), but it makes no difference. I'm now using Outlook 2010 (I was using 2007 previously) so I'm wondering if something might have changed with 2010 that is affecting how the formula works? The formula is literally identical to the one given on the above webpage.

Let me give a couple of actual examples:

1) One of my contacts has a birthday of 4 January 1989. (In my Outlook this shows as 04/01/1989 - international date format). Her TRUE age right now is therefore 24. But the formula displays her age as 23. It showed her age as 23 before her birthday last week, and it still shows it as 23 until now. But here's the weird thing: if I change her birthday, in her contact file, to be 01/01/1989 (ie. go back by three days), then her age changes to 24! And it stays at 24 for any date prior to 01/01/1989. But if I set her birthday to 02/01/1989 (or any date thereafter), then it drops down to 23. So the cross-over date is 01/01/1989. Weird!

2) Another contact has a birthday of 1 May 1989 (01/05/1988). Her TRUE age right now is therefore 24. But the formula displays it as 25 - so with this contact, it's displaying one year ahead, not one year behind as with the previous example above! But I've also found that if I change her birthday to the 2nd of the month (02/05/1988) then the formula shows the correct age of 24. Weirder still, I can change her birthday to the first day of any month between Feb-Sep 1988, and it shows her age (wrongly) as 25. But if I select any date between Feb-Sep 1988 *other* than the first of the month, then it shows the correct age of 24. And once I get to 1 Oct 1988, it shows her correct age of 24 then too. But for the first day of those mentioned months, it always shows the wrong date. So it seems to be related to the first of the month.

Can anybody (perhaps Diane Poremsky herself) help me out here please?!