Windows XP and Qt 4.1.4

If I have a QDateEdit with a displayFormat of "M/d/yy" and I try to use the spin box to increment the year, it always changes to 99 and then disables further modification with the spinner. I can modify the value manually to any number in the 0-99 range.

QDateTimeEdit appears to do the exact same thing with displayFormat = "M/d/yy h:mm:ss AP".