Error in last date modified when inserted a new tax

If you have your Opencart installed in a server with default date like DD/MM/YYYY, when you insert a new "kind of taxes" on admin, the date appears like that: 14/10/-0001 instead 14/10/2011. But if you open the tax and Save again the problem are solved.

I'm using opencart v. 1.5.1.3.