Large numbers do not work

Hi, when I enter "99,999,999.99" or "30,000,000.00" the field automatically changes to some other long number, often which is negative. Is there any way to fix this or to make large numbers (up to a billion) work? Or, at least, to inform the user that they can't enter such a large number? Right now it appears to work; only when you look at the view do you see that it's actually converted to another number. When you click the edit tab the converted number appears too, so it seems to be being stored that way in the database (but i haven't checked the database to be sure).

not sure if this is a money bug or a currency api bug, so i'm posting it to both places.
thanks!