I'll post this here for anyone having this problem. If this works, let me know and I will make it a part of the default distribution.

About line 47 of ubbt.inc.php you will see a line that looks like this:
</font><blockquote><font size="1" face="">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> if (!$w3t_language){
$w3t_language = $config[language];
}[/code]</blockquote><font size="" face="">Change that, to this:
</font><blockquote><font size="1" face="">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> if ( (!$w3t_language) &#0124;&#0124; (!ereg("[a-z]",$w3t_language)) ) {
$w3t_language = $config[language];
}[/code]</blockquote><font size="" face="">-------------------
Rick Baker
UBBThreads developer