When the 'number' property of an instance of User was incremented beyond the last user, the call to fgetuserdat() on subsequent property 'get' operation would fail and zero-out the user structure (including the user number). This resulted in an infinite loop in load/birthdays.js where the user number would go from lastuser to 1 in one operation (u.number++).

Reported by DesotoFireflite (VALHALLA)