New Card UI : Action Buttons not visible

On the planning board while adding a new card the action buttons are not visible.

From the menu Agile => Planning Board => if I click the on any main task,in pop-up UI to add new sub-task the Create , Create and Close and Close buttons are not visible, also there is no option to scroll.

It is to related the browser settings or screen resolution. Here are the details :

Display settings 1366 x 768.

Browser settings:

View => status bar is checked.

View => Toolbar => menu bar, navigation bar, youtube downloader bar are checked, rest all are unchecked.

View => Page Style => Basic Page Style

View => Encoding => UT -8

Brower details:

Firefox/3.6 (.NET CLR 3.5.30729)