IE 8 Datepicker bug

Hello!
I'm using the UI Datepicker and I found a bug in certains computers,
it's not a rule, in some "random" pcs with the IE 8, when you click to
open the Datepicker just show the first line of the month... My first
idea was a bug of my code, but I tested in the site of the UI and the
bug continues!!
Well, I don't find any solution, and don't have any idea of what to
do...
Can anyone help me??