[Lynne]

It's because of the min-height you have set in these two places:

.forumbit_nopost .forumbit_nopost .forumrow, .forumbit_post .forumrow {    
background: url("images/gradients/grey-up.png") repeat-x scroll left bottom #FFFFFF;    border-bottom: 1px solid #000000;    
border-left: 1px solid #000000;    
border-right: 1px solid #000000;    
display: block;    
float: left;    
min-height: 185px;    
position: relative;    
width: 100%;}
.forumbit_post .foruminfo {    
clear: right;    
float: left;    
min-height: 175px;    
min-width: 30%;    
width: 57%;}