Found it

The Problem was, the place of the "spanclass" Tag. The tag was/is placed behind the "a herf" Tag.
Here are the Firefox/Mozilla friendly Version:
Template: vbArticles_categorybit
Old:
Code:
<if condition="$parentcat==0"><br>
<a href="articles.php?action=viewcat&catid=$parentid">
<span class="smallfont"><b>$catname</b></span></a>
</if>
New:
Code:
<if condition="$parentcat==0"><br>
<span class="smallfont">
<a href="articles.php?action=viewcat&catid=$parentid"><b>$catname</b></a>
</span>
</if>
-------------------------------------------------------
Template: vbArticles_ARTICLESHELL
Old:
Code:
$stylevar[htmldoctype]
<html dir="$stylevar[textdirection]" lang="$stylevar[languagecode]">
<head>
<title>$vboptions[bbtitle] - $vbphrase[vbart_vbarticles]</title>
$headinclude
</head>
<body>
$header
$navbar
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
<!-- left side categories column -->
<td valign="top" width="30%">
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr><td class="tcat">$vbphrase[vbart_main]</td></tr>
<tr><td class="alt1" align="left"><ul>
<li><a href="articles.php"><span class="smallfont">$vbphrase[vbart_vbarticles] $vbphrase[vbart_main]</span></a></li>
<if condition="$permissions['vbarticlespermissions'] & CANSUBMITARTICLES">
<if condition="$bbuserinfo[userid]">
<li><a href="articles.php?action=submitarticle"><span class="smallfont">$vbphrase[vbart_submitnew]</span></a></li>
</if></if>
<if condition="$bbuserinfo[userid]"><li><a href="articles.php?action=viewfav"><span class="smallfont">$vbphrase[vbart_fav]</span></a></li></if>
<if condition="$vbart_options[vbartallowrss]"><li><a href="articles.php?action=rss"><span class="smallfont">$vbphrase[vbart_syndicate]</span></a></li></if>
</ul></td>
</tr>
<tr><td class="thead">$vbphrase[vbart_artcats]</td></tr>
<tr><td class="alt1" align="left">$catlistbit</td>
</tr>
<tr><td class="thead">$vbphrase[vbart_searchart]</td></tr>
<tr><td class="alt1" align="left">
<form action="articles.php" method="post" enctype="multipart/form-data">
<input type="hidden" name="action" value="dosearcharticle" />
<input type="text" name="keywords" size="20"><br>
<select name="searchby">
<option value="searchall" selected>$vbphrase[vbart_searchall]
<option value="title">$vbphrase[vbart_searchtitle]
<option value="content">$vbphrase[vbart_searchcontent]
<option value="author">$vbphrase[vbart_searchauthor]
</select><br><br>
<input type="submit" class="button" value="$vbphrase[vbart_searchart]" accesskey="s" />
</form>
</td>
</tr>
<tr><td class="thead">$vbphrase[vbart_authorlist]</td></tr>
<tr><td class="alt1" align="center"><a href="$vboptions[bburl]/articles.php?action=authorlist"><span class="smallfont">$vbphrase[vbart_viewauthorlist]</span></a><BR><BR><span class="smallfont">$vbphrase[vbart_viewauthorlistdesc] $vbphrase[vbart_vbarticles].</span></td>
</tr>
<if condition="$vbart_options['vbartshowstats']">
<tr><td class="thead">$vbphrase[vbart_stats]</td></tr>
<tr><td class="alt1" align="left">$statsbit</td>
</tr>
</if>
</table>
<!-- please keep intact if possible, thanks - cinq :) -->
<br><br><div align="center">
<a href="http://www.vbarticles.com" target="_blank"><img src="http://www.vbarticles.com/images/poweredby.gif" border="1"></a></div>
<br><br>
<!-- please keep intact if possible, thanks - cinq :) -->
</td>
<!-- /left side categories column -->
<!-- right side content column -->
<td valign="top" width="70%">
$ARTICLEHTML
</td>
<!-- right side content column -->
</tr>
</table>
<br>
$footer
</body>
</html>
NEW:
Code:
$stylevar[htmldoctype]
<html dir="$stylevar[textdirection]" lang="$stylevar[languagecode]">
<head>
<title>$vboptions[bbtitle] - $vbphrase[vbart_vbarticles]</title>
$headinclude
</head>
<body>
$header
$navbar
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
<!-- left side categories column -->
<td valign="top" width="30%">
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr><td class="tcat">$vbphrase[vbart_main]</td></tr>
<tr><td class="alt1" align="left"><ul>
<li><span class="smallfont"><a href="articles.php">$vbphrase[vbart_vbarticles] $vbphrase[vbart_main]</a></span></li>
<if condition="$permissions['vbarticlespermissions'] & CANSUBMITARTICLES">
<if condition="$bbuserinfo[userid]">
<li><span class="smallfont"><a href="articles.php?action=submitarticle">$vbphrase[vbart_submitnew]</a></span></li>
</if></if>
<if condition="$bbuserinfo[userid]"><li><span class="smallfont"><a href="articles.php?action=viewfav">$vbphrase[vbart_fav]</a></span></li></if>
<if condition="$vbart_options[vbartallowrss]"><li><span class="smallfont"><a href="articles.php?action=rss">$vbphrase[vbart_syndicate]</a></span></li></if>
</ul></td>
</tr>
<tr><td class="thead">$vbphrase[vbart_artcats]</td></tr>
<tr><td class="alt1" align="left">$catlistbit</td>
</tr>
<tr><td class="thead">$vbphrase[vbart_searchart]</td></tr>
<tr><td class="alt1" align="left">
<form action="articles.php" method="post" enctype="multipart/form-data">
<input type="hidden" name="action" value="dosearcharticle" />
<input type="text" name="keywords" size="20"><br>
<select name="searchby">
<option value="searchall" selected>$vbphrase[vbart_searchall]
<option value="title">$vbphrase[vbart_searchtitle]
<option value="content">$vbphrase[vbart_searchcontent]
<option value="author">$vbphrase[vbart_searchauthor]
</select><br><br>
<input type="submit" class="button" value="$vbphrase[vbart_searchart]" accesskey="s" />
</form>
</td>
</tr>
<tr><td class="thead">$vbphrase[vbart_authorlist]</td></tr>
<tr><td class="alt1" align="center"><span class="smallfont"><a href="$vboptions[bburl]/articles.php?action=authorlist">$vbphrase[vbart_viewauthorlist]</a></span><BR><BR><span class="smallfont">$vbphrase[vbart_viewauthorlistdesc] $vbphrase[vbart_vbarticles].</span></td>
</tr>
<if condition="$vbart_options['vbartshowstats']">
<tr><td class="thead">$vbphrase[vbart_stats]</td></tr>
<tr><td class="alt1" align="left">$statsbit</td>
</tr>
</if>
</table>
<!-- please keep intact if possible, thanks - cinq :) -->
<br><br><div align="center">
<a href="http://www.vbarticles.com" target="_blank"><img src="http://www.vbarticles.com/images/poweredby.gif" border="1"></a></div>
<br><br>
<!-- please keep intact if possible, thanks - cinq :) -->
</td>
<!-- /left side categories column -->
<!-- right side content column -->
<td valign="top" width="70%">
$ARTICLEHTML
</td>
<!-- right side content column -->
</tr>
</table>
<br>
$footer
</body>
</html>
-------------------------
Template: vbArticles_favbit (This one looks realy bad in Firefox)
Old:
Code:
<tr>
<td class="alt1" align="left" width="50%"><a href="articles.php?action=viewarticle&artid=$favarticleid"><span class="smallfont">$title</span></a><if condition="$updated==1"><span class="smallfont"> - <i>$vbphrase[vbart_updated]!</i></span></if><br><span class="smallfont">$vbphrase[vbart_category]: <i>$category</i></span></td>
<td class="alt1" align="center" width="20%"><span class="smallfont">$author<br></span><span class="time">($date)</span></td>
<td class="alt1" align="center" width="20%">
<a href="articles.php?action=printarticle&artid=$favarticleid" target="_blank"><img src="$stylevar[imgdir_button]/printer.gif" border="0" alt="$vbphrase[vbart_printart]"></a> <a href="articles.php?action=sendarticle&artid=$favarticleid" target="_blank"><img src="$stylevar[imgdir_button]/sendtofriend.gif" border="0" alt="$vbphrase[vbart_sendarticle]"></a>
</td>
<td class="alt1" align="center" width="10%">
<input type="checkbox" name="chkarticleunfav[]" value="$favarticleid">
</td>
</tr>
New:
Code:
<tr>
<td class="alt1" align="left" width="50%"><span class="smallfont"><a href="articles.php?action=viewarticle&artid=$favarticleid">$title</a></span><if condition="$updated==1"><span class="smallfont"> - <i>$vbphrase[vbart_updated]!</i></span></if><br><span class="smallfont">$vbphrase[vbart_category]: <i>$category</i></span></td>
<td class="alt1" align="center" width="20%"><span class="smallfont">$author<br></span><span class="time">($date)</span></td>
<td class="alt1" align="center" width="20%">
<a href="articles.php?action=printarticle&artid=$favarticleid" target="_blank"><img src="$stylevar[imgdir_button]/printer.gif" border="0" alt="$vbphrase[vbart_printart]"></a> <a href="articles.php?action=sendarticle&artid=$favarticleid" target="_blank"><img src="$stylevar[imgdir_button]/sendtofriend.gif" border="0" alt="$vbphrase[vbart_sendarticle]"></a>
</td>
<td class="alt1" align="center" width="10%">
<input type="checkbox" name="chkarticleunfav[]" value="$favarticleid">
</td>
</tr>