To overcome this issue with DISQUS v4, use the Narcissus theme and add the following Custom CSS (Login > Settings > Appearance):
#dsq-new-post div, .dsq-clearfix:after, #dsq-form-area div {clear: none!important;}
.dsq-popup[id] {top:0!important;} /*Make bottom of login box visible*/
.dsq-login-box {width:600px!important;} /*Make room for buttons and login textboxes*/
ul.dsq-login-buttons {overflow:hidden;} /*Fix spacing after required float in last li*/
ul.dsq-like-faces li {background-image:none!important;} /*Override webtemplate li style*/
.dsq-popup[id] {top:0!important;} /*Make bottom of login box visible*/
.dsq-login-box {width:600px!important;} /*Make room for buttons and login textboxes*/
ul.dsq-login-buttons {overflow:hidden;} /*Fix spacing after required float in last li*/
ul.dsq-like-faces li {background-image:none!important;} /*Override webtemplate li style*/