[ForceHSS]

You put it to far up it needs to be above

<vb:else />
                <span class="username guest">{vb:raw post.musername}</span>

So it looks like

<vb:if condition="$post['field5']"> 
<font color="red" size="4"><B>{vb:rawphrase field5}[{vb:raw post.field5}]</B></font></vb:if>
            <vb:else />
                <span class="username guest">{vb:raw post.musername}</span>

also you said you used profile field 5 but in that ss you have it as 4