[fireknight]

Sorry mate my bad.
I forgot that textarea does not support bbcode or html code.

You may have to look at doing a work around.

Again sorry for my mistake.

EDIT

I have found a work around solution.

Add this to global.php
( change the colors to suit your existing classes & remove the spaces from the [ ] tags )

function get_user_class_name_commentbox($class)
{
  switch ($class)
  {
    case UC_USER: return "[ color=#8E35EF][ b]User[ /b][ /color]";

    case UC_POWER_USER: return "[ color=#f9a200][ b]Power User[ /b][ /color]";

    case UC_VIP: return "[ color=#009F00][ b]VIP[ /b][ /color]";

    case UC_UPLOADER: return "[ color=#0000FF][ b]Uploader[ /b][ /color]";

    case UC_MODERATOR: return "[ color=#FE2E2E][ b]Moderator[ /b][ /color]";

    case UC_ADMINISTRATOR: return "[ color=#B000B0][ b]Administrator[ /b][ /color]";

    case UC_SYSOP: return "[ color=#FF0000][ b]SysOp[ /b][ /color]";
  }
  return "";
}

userdetails.php

Find

$modcomment = htmlspecialchars($user["modcomment"]);

Change To

$modcomment = format_comment(htmlspecialchars($user["modcomment"]));

Find

<textarea cols=60 rows=6 name=modcomment>$modcomment</textarea>

Change To

<div name='modcomment' style='overflow-y:scroll; height:200px;'>$modcomment</div>

modtask.php

Find

$modcomment = gmdate("Y-m-d") . " - $what to '" . get_user_class_name($class) . "' by $CURUSER[username].\n". $modcomment;

Change To

$modcomment = gmdate("Y-m-d") . " - $what to '" .  get_user_class_name_commentbox($class) . "' by $CURUSER[username].\n".  $modcomment;

Now the only issue is !
The comment area now becomes Read Only.
And cannot be edited from the userdetails.php page.
But hey you cannot have everything.