IE problem

I have a following problem:

I create mainwindow and immediately create modal dialog for login.

This dialog has two textfields for username and password and “Login” button .

I enter username and password and press button.

I then try to login with values from textfields.

On Firefox and Chrome, the values I get on server are ok. On IE, they are blank.

The strangest thing is, if i navigate with TAB key, even on IE works. But if I navigate just with mouse, the value never gets posted to server (on IE).