Per Ozzy47 however - he solved another issue this has with Firefox browser and styles that use border pinstriping for the posts? The edit to postbit_legacy was breaking the border, as in the image below where you see the cursor and in the post above. This break does not appear however in chrome or even IE.
To fix this
Find in postbit_legacy:
HTML Code:
<tr>
<td class="alt1" valign="bottom">
$template_hook[postbit_signature_end]
</td>
</tr>
Replace with:
HTML Code:
<tr>
<td class="alt1" valign="bottom" style="border-right: $stylevar[cellspacing]px solid $stylevar[tborder_bgcolor]; border-top: 0px">
$template_hook[postbit_signature_end]
</td>
</tr>
Kudos and much thanks to ozzy47 for fixing this.