Probably you have Pop-up blocker enabled. You should disable them, following one of these instructions:
From Tools menu click Pop-up Blocker, choose Turn Off Pop-up Blocker and try again. If not see Tools menu, press ALT key from the keyboard to turn on Menu bar under address bar;
From View menu click Toolbars and check whether there are toolbars, different from the standard ones (for example: ICQ Toolbar, Google Toolbar, Yahoo Toolbar, Flashget Toolbar, Norton Toolbar, Bitcomet Toolbar etc.) and turn off them by clicking on the ticks. Then restart browser Internet Explorer and log into Internet banking again.
From Tools menu click Manage Add-ons (then Enable or Disable Add-ons - about Internet Explorer 7) and open list of installed plug-ins in your browser.
Check whether there are in the list toolbars like: ICQ Toolbar, Google Toolbar, Yahoo Toolbar, Flashget Toolbar, Norton Toolbar, Bitcomet Toolbar etc. and turn off them
by marking them and choosing Disable option (or button) under the list.