Ciao, io ho risolto il problema della pagina eliminando dal file degli stili components\com_docman\themes\default\css\theme.css lo stile dm_form br che riguarda il form:
.dm_form {
margin: 0 auto;
width: 35em;
padding: 1em 1em 1em 1em;
border: 1px solid #cecece;
}
.dm_form fieldset { border: 0 none; margin: 0; padding: 0.5em;}
/*
.dm_form br { display: none; }
*/
.dm_form label { display: block; width: 100px; font-weight: bold; float: left; }
.dm_form label.nofloat { float: none; }
.dm_form p { text-align: left; }
.dm_form fieldset.dm_button { border-top: 1px solid Gray; }
.dm_form select option.label { background-color: #EEE; border: 1px solid #DDD; color : #333; }
.dm_form .editor { float: none; }
Lorenzo