You need to check your templates usually in default vb its in
forumhome but since urs is customized check the template
forumhome_forumbit_level1_nopost
Code:
<tr align="center">
<td class="thead"> </td>
<td class="thead" width="100%" align="$stylevar[left]">$vbphrase[forum]</td>
<td class="thead">$vbphrase[last_post]</td>
<td class="thead">$vbphrase[threads]</td>
<td class="thead">$vbphrase[posts]</td>
<if condition="$vboptions['showmoderatorcolumn']">
<td class="thead">$vbphrase[moderator]</td>
</if>
</tr>
You need to add defined pixel or % to your cells.
like width="200px" for latest thread cell and so on.