Fatal error when running cron.php

That's an easy one to fix.
Please go to line 772 of birthdays.module and remove the first underscore '_' from the function call.

Thus changing

$users = _birthdays_get_todays_birthdays();

to

$users = birthdays_get_todays_birthdays();

I thank you very much for reporting these bugs! Don't hesitate to keep doing that when you find things that aren't in order.

Great to hear!