Misplaced modifier message

We're getting the following message at the top of the forum when you go into any thread:

Warning: Unknown modifier 'r' in /home/charming-holly.com/html/forum/admin/funtions.php on line 825

And this is the code in functions.php. I bolded line 825.

if ($phpversionnum<"4.0.5") {
$bbcode=str_replace("'", "\'", $bbcode);
}
$bbcode=preg_replace($searcharray, $replacearray, $bbcode);

if($dobbimagecode and ($bbuserinfo[userid]==0 or $bbuserinfo[showimages])) {
// do
$bbcode = preg_replace("/\[img\](\r\n|\r|\n)*((http|https):\/\/([^;<>\(\)\"".iif($allowdynimg,"","!\*\?\&")."]+)|[a-z0-9\/\\\._\- ]+)\[\/img\]/siU", "<img src=\"\\2\" border=\"0\" alt=\"\">", $bbcode);

I'm not sure what could've caused this. The only thing that any admin has done recently is that I added the last visited date to the forum home page and changed the format of the date. Any help would be much appreciated.